Local shops are pretty great at making sure you've got what you need when it comes to ram, especially if you come back within their return period. I once had to go through three different sticks to find a ram upgrade that'd work in an old Athlon700 I had, and the people at the shop were helpful the whole way through.

I kind of miss well-stocked, well-staffed, small computer shops that carry a good mixture of used and new stuff. They pretty much don't exist in Arizona. There's the occasional unfriendly guy who starts a computer shop and sells off his old crap along with stuff he buys on eBay or whatever, overpricing the whole way. But nothing really good.