Not completely sure about the RAM, but I'll do some searches and get back to you.
As for the hard drive... definitely SATA. There is SATA 150 and SATA II, although SATA 150 should be fast enough. What kind of hard drive do you plan on getting?
AMD Athlon 64 3000+ socket 939 @ 2.3 GHz
MSI K8N Neo2 Platinum motherboard
EVGA GeForce 6800 GT
2 GB DDR 400 (PC 3200) (2 x 1 GB sticks) (Dual Channel)
DVD player and seperate DVD RW drive
80 GB Western Digital Hard Drive
500 watt power supply
Sound Blaster Audigy
Logitech 5.1 surround sound speakers
SAMSUNG SyncMaster 710T LCD monitor
Aspire X Navigator Case