so, basically decide right when i am ready to do it..
If you need one now, just get it. No computer will stop when new one will be available.
Just get one now, then use it. When it start to feel slow, maybe in 2 years, then just get another one..
If you wait for something better, you'll be waiting forever. now, there is X2. then AM2, then Conroe, then who care, then who care again ...