IDE hard drives have data transfer rates of 100 (typical) or 133 Mb/s. SATA came long and gives us 150 right out of the box. the newest, SATA2, is out now, offering 300Mb/s transfer rates.
sata doesnt cost anymore than the IDE drives, as its the new standard, as we are moving away from IDE hard drives. the usual good brands of hard drives still apply- maxtor, seagate, etc.
sata2 is still pretty new, so there is not wide support for it yet, but that will change soon. I know some asus mobos already support it, and I have seen hitachi hard drives at the sata2 standard on newegg. even the sata2 drives are about the same cost!
one thing, you may need a floppy drive to install the SATA drivers for the windows install. just a heads up.
doby is the real master of psu, so check some power question threads he was in. I think its mostly about the number of amps on the 12v rails, especially for a higher end AMD. if you can spring for the better psu now, might as well, then you wont need to upgrade later! make sure to get a good brand, like antec, thermaltake, enermax.