Task Manager, check for programs hogging the CPU.
You can slim down Windows to help with CPU. There is a program called nLite that will strip out components you do not want from a Windows install CD to make a more lightweight windows.
There are also pre-build slim Windows called TinyXP and MicroXP floating on torrent sites (MicroXP can run on something like 32mb). The liter you go, though, the more problems you're likely to have getting some programs to work that may rely on features you strip out, FYI.
For an easier approach you can try checking your
autoruns (Login tab has most of the stuff you'd want to check) and disabling any third party stuff you don't want. Frequent offenders are Google Update, Adobe Update/Tray, QuickTime Tray, Java Update.
There are also several lists of Windows XP services online that can help you identify services you can disable. I myself usually need only 3 svchost processes running... all the system/services processes total take up about 37mb.
Here's a list of services I keep running on XP Home (XP Pro might need a couple more or something):
- Automatic Updates (powers Windows Update)
- Background Intelligent Transfer Service (powers Windows Update)
- COM+ Event System (I think a lot of stuff would break, especially in Explorer, if you stop this.)
- Computer Browser (Helper for File and Folder Sharing Client... if you disable this you may not be able to use Explorer to browse other computers on the network unless you type in the name/IP manually.)
- Cryptographic Services (Stores passwords for Remote Desktop connections and I think some IE passwords too for 401 sites. I think it also verifies IE HTTPS connections.)
- DCOM Server Process Launcher (Sames notes as for COM+)
- DHCP Client (Used to retrieve IP/Gateway info from your network, if you can hardcode that information in network properties you can turn this service off.)
- Event Log (Powers the Event Log snap-in console. You might be able to disable this but I think other services complain if you do. Leave it be.)
- Fast User Switching Compatibility (You can turn this off but if you do you will no longer be able to "Switch User" or connect to your computer using Remote Desktop without logging out first.)
- Machine Debug Manager (Needed for Visual Studio, maybe some other debugging apps, not an OS service but an application one, disable it and see if it causes problems, reenable if it does.)
- Network Connections (Do you like having internets? Keep this on.)
- Plug and Play (Do you like having stuff work when you plug it in? Keep this on.)
- Remote Access Connection Manager (More network stuff.)
- Remote Procedure Call (RPC) (Windows internal stuff, I think it breaks lots of Windows apps if you disable this.)
- Security Accounts Manager (Powers User Accounts, leave it on.)
- Server (Allows your computer to share files and printers, turn it off if you don't share anything.)
- Shell Hardware Detection (Do you like your hardware to keep working? Keep it on. Also powers autoplay.)
- System Event Notification (More system required stuff.)
- System Restore Service (Powers System Restore. Turn it off if you don't need it (disable it in System Properties first).)
- Task Scheduler (Powers the Task Scheduler, not required to be running but it will break a lot of apps if you don't. Mostly updaters maybe but some Microsoft stuff uses it too.)
- Telephony (I don't think you need this if you don't use dial-up but I have it enabled anyway.)
- Themes (Allows Windows Themes. You should probably disable on an EEE. Should speed things up a little.)
- Windows Audio (Do you like sound? etc)
- Windows Management Instrumentation (Allows programs to access some hardware statistics though any app can add information to WMI for other programs to access. Some programs will break if this is disabled.)
- Workstation (More networking stuff for File and Printer sharing client.)
Here are some services I disabled but you might still need:
- Distributed Link Tracking Client (Syncs shortcuts when you move files around that shortcuts point to. If this is off the shortcuts will break and you'll have to fix them by hand, no big deal.)
- Error Reporting Service (Allows for you to send error reports to Microsoft. Turning it off reverts to a dialog without that option when a program crashes.)
- Help and Support (Allows for you to use Windows Help. I keep it off and only turn it on if I need it, then turn it off afterwards.)
- Indexing Service/Windows Search (Search stuff that will index your hard drive. If you don't want large cache files on your drive or the slowdown of indexing and don't care that searches will take a little longer, disable them.)
- IPSEC Services (Network security stuff your little home network probably doesn't use, disable it.)
- Messenger (Allows people halfway across the world to pop up dialog boxes on your screen.)
- Network Location Awareness (Although required in Vista or else networking breaks, it is less tightly integrated in XP and can be disabled.)
- NVIDIA Display Driver Service (NVIDIA's service does some trivial things or something. Disable it and you'll likely notice no change.)
- Print Spooler (Printer support, disable if you don't print or send faxes.)
- Remote Desktop Help Session Manager (Powers Remote Assistance, turn it off unless you think you'll need it.)
- Secondary Logon (Powers "Run as" menu option to run programs as another user. Poor man's UAC.
- Security Center (Tray icon that nags you if your anti-virus is out of date.)
- SSDP Discovery Service (If you don't have UPnP devices on your network or don' t know what that means you can probably disable this.)
- TCP/IP NetBIOS Helper (For legacy apps that use NetBIOS, I think. Noone uses it anymore so disable this.)
- Windows Firewall/Internet Connection Sharing (Powers both of the aforementioned, disable if you don't need them.)
- Windows Image Acquisition (Powers incoming fax and scanners and other hardware that uses the WIA to download images to your computer (some old cameras, though most allow you to browse the folders in Explorer now).)
- Windows Media Player Network Sharing Service (Hi I'm a PC, I'll share all your "movies" on your network for you! Thanks for using WMP!)
- Windows Time (Syncs your time with the internets.)
- Wired AutoConfig (Not sure what this does, DHCP works fine for me thx.)
- Wireless Zero Configuration (Powers wireless networking adapters, disable if you don't have any.)
Again, check one of those service lists for more comprehensive lists, and make sure to use System Restore to set a restore point so you can undo the changes if needed. If you screw it up so it's unbootable using "Last Known Good Configuration" should undo the changes as well.