cheapest main build, i say get Gigabyte GA-p35-DS3l (less than 90$ CAD)
cpu: e2160 and then overclock it to 2.9 ghz easily on stock cooling and BANG! fast comp!! it's almost as good as an e8400 stock and you save lots of cash
for more info
http://forums.anandtech.com/messagev...&enterthread=y
as for vid cards, i'd say wait till more mid-priced multi-core graphics cards are released.