So after nearly a decade, I'm finally deciding to upgrade my computer. I'm mostly just looking for lifespan and stability, and I'm holding off getting a new monitor (and perhaps things like keyboard and mouse) until probably Cyber Monday rolls around. I'm mostly curious what you all think of the parts I'm planning to get to build my new computer:

Case: Antec Dark Fleet DF-35 Black Case
Power Supply: Antec BP550 Plus 550W Continuous Power Modular Active PFC PS
Motherboard: Asus M4A79XTD EVO AM3 790X ATX
Processor: AMD Phenom II X6 1100T Black Edition Thuban 3.3GHz, 3.7GHz Turbo Socket AM3 125W
Memory: Kingston HyperX 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1800
Video Card: MSI R5770 Hawk Radeon HD 5770 1GB 128-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support
Optical Drive: LITE-ON Black 12X Blu-ray Burner with Blu-ray 3D feature SATA Model iHBS112
HDD#1 (OS): OCZ Vertex 2 OCZSSD2-2VTXE60G 2.5" 60GB SATA II MLC Internal Solid State Drive (SSD)
HDD#2 (store): Western Digital Caviar Black WD5002AALX 500GB 7200 RPM SATA 6.0Gb/s 3.5"
CPU Cooler: COOLER MASTER Hyper 212 Plus RR-B10-212P-G1

I'll be getting this stuff pretty soon to capitalize on sales and such, and I'm probably not changing this list unless I get a unanimous outcry against something on this list, just so you all know.

Looks to be all high quality stuff and compatible. What's the purpose of this PC?
Asking because I question the choice of a Phenom II X6 vs i5-2500.

Besides replacing my ancient main desktop computer I primarily use for everything? It'd be nice to play new PC games, and I'd like to try dabbling in 3D modeling and the like again. But on average, I'd use it for the usual computer things: e-mails, watching videos (online and offline), plotting world domination...

Plans to Crossfire 5770's in the future? AMD recommends 600w for that, although I bet that 550W Antec could handle it. I was thinking you might be better off with an X4 and putting the extra money into something else like a slight better videocard but if the focus is more on multitasking than gaming, stick with your original plan.

Yeah, multi-tasking is definitely a higher priority than gaming for me. Thanks!

Get an i5.

Yes, definitely get an i5.

I metaphorically rape my computers, doing stuff like parallel builds and transcoding. I recently went from 8-core Xeon to 4-core i5, same performance per core in benchmarks, and I've noticed zero difference. That means I never needed any more than 4 cores.

If I don't need 6 cores, you definitely don't. So hopefully that isn't a factor in your decision.

You can easily OC a 2500K to a higher clock speed then that Athlon using the same cooler too.