Yeah, he's going to need to put down more than $200 for SC2 to run reasonably well.
Here's what I put together:
Mobo (MSI G31TM-P21 - $47.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16813130234CPU (Intel Pentium Dual-Core E6600, 3.06GHz - $88.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16819116347Video Card (XFX ATI RADEON HD 4670, 1GB DDR3 - $74.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16814150449The subtotal for that is going to be around $211.97, shipping to Midland is around $14.59 via Purolator (or $17.79 via UPS), and $29.46 tax, for a total of $256.02.
If he doesn't already use DDR2 RAM, he's going to need memory:
2GB (1x2GB - $32.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E168201413004GB (2x2GB - $63.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16820141337So, there you go. That should prove to be a pretty decent machine for the price. He might be able to save $30-ish by bumping the processor down to a 2.7GHz model, but since dual cores are starting to get slowly and steadily phased out, I'd probably stick with the 3.06GHz one to compensate for that a bit. I believe the 46XX RADEONs are still a bit better than the 55XX RADEONs, so if he wanted to jump up to the next generation, he'd have to get at least a 5600 series card to keep up.
Speaking of the video card, I did factor NVIDIA's offerings -- from the GTS 250 and on -- into the search, but ATI's cards were simply a better value.
I would most definitely replace the video card. I run an X300 in my laptop and that's probably going to be half his problem right there. I think WoW is the only somewhat modern game I have that'll still play on it (even Cataclysm works, surprisingly!), and only because Blizzard needs to cater to the Intel "Extreme" Graphics users, the likes of which my venerable X300 can still outperform in some workloads.