Why so small? The sweet spot for drives right now is around 500-640GBs. I've seen 500GB drives on newegg for $50 shipped. Not much point in getting a 160 or 250GB. I stick with Seagate or WD drives myself. Try to buy from the newest lines.
not the newer hard drives they tend to be on higher density platters wich gives greater response and speed the seagate 7200.12 500gb is one of those and the samsung f3 500gb but if you want a smaller hard drive you cant go wrong with the samsung f3 250gb
Then you heard wrong. A slower CPU will take longer to format a larger drive, but I wouldn't let that stop you. I'd get the best performing drive you can that has lots of space. Obsidian pointed out a couple of good ones. As for Cache, latency, rotation speed, etc, your worrying about this to much. The Seagate 7200.12 and WD AAJS(?) drives are fine. Don't worry about 7200RPM vs 10000, or 16mb cache vs 32, etc. Find a 7200.12, AAJS, or F3 drive that you can afford and be happy.