thx guys.. all of u have been very helpful.. and sorry for my noobness..

anyway i've complete my new rig, and here is the specs:

QX6700
Gigabyte p35 dq6
2gig tracer pc5300 (temporarily, already ordered pc8500)
HIS HD x2900xt
thermaltake toughpower 700w

and so far i've tested @ 450x7, PI stable at stock voltage..will try to go higher..