I think that upgrading, like many other things, tends to yield less benefit after a certain point is reached. I have seen many instances over the years where the same old computer is OK for a user’s “current” needs. Then, the user one day finds a new thing/task to use their computer for… only to find that it can’t perform the function. It seems to be more rampant on a forum, since there are so many of us. And, it seems some one is updating the hardware just about every day.
Myself (and, I think a fair amount of us on these forums) are novices or small-time entrepreneurs. So, I found myself in that situation a few years ago. I bought my first 8-track card and recorded my first group of artists. Suddenly, 9GB of HDD space was no enough. Then, I went to 16 tracks and the drive bandwidth wasn’t enough. Then, it seemed to take too long to process effects and filters. But, today, my 20 month old 1.9GHz P4 with dual 80GB RAIDs can record 16 tracks of DVD quality audio. And, my outboard gear is behind the times. 3GHz would be nice. But, not necessary… for me.
The flip side of constant hardware rotation is that you could possibly keep your gear from getting too old. With computers, age can sometimes work against you with failures. But, I’ve seen new stuff fail plenty of times. It is kind of a fine line between knowing what works and when it would be beneficial to step up on the gear line.
So, I think I am agreeing with you in that you probably should hold off upgrading your computer if it is doing what you need to get the job done. If you going to get a new project that required you to add a function you don’t already have, that might be a time to consider upgrading. But, give enough time to get the new system stabilized. I would be worried about jumping into a new environment with a bunch of bugs and quirks to riddle the project.
New gear is fun, though… :p