need some feedback on m/b and memory purchase

hi im about to purchase a few upgrades to get me through the college year( im trying not to buy another graphix card b4 (sli) my current setup is as folllows. soyo kt400 dragon ultra an athlon 2600+(360 fsb @2.25 ghz non barton) and 1gig of pc2700 corsair 2-2-2-6@ 360mhz ddr.a geforce fx 5900 (400core 960 mem)i am trying to get more doom 3 preformance. the upgrades im thinking about are
an msi nforce 2 ultra 400 chipset board and 1 gig of ddr400 (ocz enhanced latency) to put in dual channel. do u guys think this is a wise choice ? if not pls post what u think i should buy spending only about $300
thanks!