I want to be able to play some PS2 game ports on my PC (specifically: MGS2, Onimusha3), and trying to do so with keyboard and mouse is quite a *****. Which controller would you recommend?

A dual-analog one I saw at a store yestereday looked pretty good, and it costs under $25, too.

There were a few Logitech ones as well, but those seemed much more expensive.

I have a Wingman Cordless and I love the thing.

i'd just get a ps2 one and a converter

Logitech has a bunch of PS2 gamepad clones to look at:

http://www.logitech.com/index.cfm/products/productlist/US/EN,crid=2216,categoryid=429

That's exactly what I did. I love the PS2 controller.

I never heard of a converter before. Never saw one on sale anywhere around here, either. Do they sell those things in hardware shops?

An adapter might be a better description. Something like this, except I'm assuming you'll need to find a US site that sells them.

they usually sell shedloads of those adaptors on ebay

The Xbox360 controller for Windows IMO is perfect. I can use it all day and my hands won't get tired. Plus the build quality is amazing. A bit expensive, but its a awesome controller.

I plug my Xbox controller in. I have a PS2 shaped controller for my pc, but it's really flimsy. I love the Xbox controller S. It even has rumble in games that support. (i.e. N64 roms)

They're all over the place on the intarweb.

http://www.lik-sang.com/comparison.php?item_grp_id=2

There's a nice comparison on the Lik-sang import site.