as of right now current hard drives arnt fast enough to max the Sata 1 bus of 150Mbps
so basically all sata II does is double the already too large sata 1 bus to 300Mbps.
you can think of it this way, there is a waterpipe that runs to the septic tank.
the water pipe sometimes at a maximum gets half full, when alot of people are taking showers, craps, and washing dishes
well the plumber came in and doubled the size of the water pipe.
that new water pipe is Sata II
(so you may as well get it, its not more expensive or anything)
Ohh and as far as videocards.
you cant beat these for the money.
(1800XT in sheeps clothing)
(my link is cheaper than Nik00117s Link
and Get the Ram thats rated at 800MHZ.
PS- Vista and more games are becoming very memory hungry, 2GB ram in systems will be the new standard before long.
good luck man