Charity:Being in a similar position, I searched around and couldn't find anything reasonable. (Some overpriced eBay stuff, but that's it.) I found it was more economical to replace mainboard and CPU (and thereby PSU and RAM too, as the ones I had wouldn't work with the new stuff).
Motherboard+CPU+RAM is definitely the way to go if you're stuck on an older AMD socket.. There were some dual-cores released for 939 that you could upgrade to, but they're pretty hard to find and can be quite expensive.. It's often cheaper and you get more for your money when you just buy current generation hardware. That being said, you shouldn't need to upgrade your PSU.. The 939 chips didn't really draw any less power than most of the AMD chips on the market right now.. If you combine it with a fairly high end graphics card, then of course, you'll likely need a new PSU too.
When you can get a 2.6 Ghz quad-core for $99 and 4 gigs of DDR3-1333 for $70 and an AM3 motherboard for $100.. It makes no sense to stick with that old DDR-333 memory..
Onboard RAID vs. 3Ware RAIDI never recommend people run RAID-5 with onboard chipsets.