Right now is the time to upgrade. Even if you wait another month or so, Intel is planning on slashing prices on their processors and I would expect AMD to follow suit as, they have a new socket coming out. I would certainly upgrade.
Personally I believe (my opinion here no arguen' about a guys opinion)
that right now is a hard time to upgrade, esp with new sockets coming out
you already have a capable CPU - upgrading it would mean watching a whole new line of CPUs coming out in a short time here - (example) new AMD cpu for you would mean a socket 939, and they haven't droped the prices on the 939 CPUs yet. AM2 is coming out soon. So yur in a bit of a pickle there
A fairly capable Vid Card upgrade means a decent PCIx card - which means a new motherboard - (again the same problem) why buy a new motherboard if you aren't going to go with a socket 939
Memory could definately use an upgrade there (BUT *here's this word again*) new socket changes involve DDR2 memory.
I spose what i would do if i was in your place is to buy a capable Single PCIx16 motherboard somewhere in the $60-$80 range, buy the cheapest 939 CPU, get 1gig of RAM, and get the absolute best price/performance video card you can afford (since this can make the move to a new system should you upgrade to a new socket later)
Crazy time to upgrade right now, but if you were to purchase something along the lines of what i have listed above, you can also wait a couple months when the new sockets come out and current 939 CPU prices drop and end up having a great CPU for alot less than you will pay now.
Well, it depends. If your ready to upgrade right now, then yes, do it now while the prices are reasonable and there are good processors out.
The thing is, none of us really know what to expect from the new processors coming out as of yet. Me personally, I wouldn't wait because, chances are when they do come out, they will be far more expensive, could have bugs and may not perform that much better than what we have out now. Never know till the time comes.
Even right now if you build a machine, it will still be very competitive for the next two years or so. If you have the cash now and just want to spend it, do so.