here is how things in hardware goes..
lets say you upgrade now.. get a $500 vid card, afue months down the track that card will go from $500 to $200.. Now I'm not saying that $500 will be bad in afue months, ****.. I was using a geforce 2 mx 440 for 5 years!..
Anytime is a good time to upgrade, but I must say.. for overall, parts are cheap.. and there wont be any new major price crippling things coming out for a while.