at 1600x900 and looking at oyur system its a pretty good match, at that ers you should be able to play games in mid-high settings for what's out now... as for the rest of the yea thats mostly speculation as we don't knwo what kind of engine changes and flat out new engines will come out, crysis 2 will probably be the beast to tackle and i don 't knwo enough abotu it to comment if you'll be playing on medium settings or lwo settings, but i think you'll be able to get playable frame rates with even that title (given lower bar settings)
with ram being as cheap as it is if your board will support 4 gigs i'd up it to at least that as well
id say medium settings, yes, max settings, definitely not. i would get a ati 5770 over that 450, or even better a gtx460se. any more than that and your cpu will bottleneck the gfx card at that resolution.