You're asking us if we can predict whether or not your laptop will breakdown in the next year or two?
Is this the psychic laptop forum?
If you take good care of your laptop...
-clean out the dust monthly
-don't block the fans
-don't drop it
-gently open it so you put the least amount of stress on the LCD
-don't eat messy food near it
-run virus/spy/defrag programs on it
-gently clean your LCD
...you probably shouldn't expect any problems, but i'm not psychic, so i can't be sure.
You might want to look into extending it a year, so when the time is up you can get vista and dx10 platforms that have all the bugs worked out of them. Or that might be a reason not to extend it, you may want the first gen vista oriented hardware and dx10 cards.
Personally though it seems smarter to extend it a year and after that purchase a new system with a bug free dx10 card. The consensus is that your dx9 card with last a while since companies don't want to right away completely hose people who have dx9 cards.