Sifu & pro...can help me out pls?

1. Brand : Asus
2. Budget : 2300 +/-
3. Usage : Gaming, programming, flash, photoshop, HD movies...(IT student here)
4. Spec : prefer 15", gt540m, i5

I was looking to replace my vaio cr32 cuz it couldn't keep up with my tasks n crawls like a turtle
Booting the vista is a pain in the @ss cuz it took more than 5 min @#@&% Thts y i always let it hibernate
I've tried several software maintaining, cleaning, updating it but stil the same...hvn try format it cuz hvn got a place to do backup yet.

Initially was eyeing for N53 but saw N55 coming soon but price is on the high side for me & i like N53 design more...but N55 spec is better...arghh ...just wanted to get 1 which stil can keep up after 3 to 5 years...

Appreciate yr advice

GT540M with 1gb and 2gb really got big difference? My fren juz bought a 4830tg told me there is big diff & saw another sifu said its like jln biasa vs highway...but as far as i know, the diff is not prominent. Can anyone clarify this?