Is a CPU upgrade worthwhile

I've made a few upgrades to my computer (probably not the best ones, but I'm a first timer and it was a good learning experience). so this is what I now have:

Intel Pentium 4 550 @ 3400MHz
Gigabyte 8I915P-G mobo
2GB DDR Ram
NVIDIA GeForce 8800GT video card



My question is, should I next (given that I'm basically looking for a speed kick to tide me over to a new purchase in about a year):

a) upgrade the CPU (which I'm keen to do if the benefits are significant enough)
b) upgrade the CPU and motherboard (which I'm less keen to do simply because of the difficulty)
c) not upgrade anything - the next step is to get a new computer (which I'm not that keen on because of money, and the fact I'm planning to go overseas soon).

Wait untill the Nehalem's coming in next year.

If you are going to use the config for few years or so, then just do some minor upgrades that will be extremely important according to your needs. I think upgrading CPU will be enough (if the new one supports your existing mobo).

Thanks - there are a couple of CPUs I've looked at that are supported by my mobo and are a decent bit faster than what I have at present, so I'll go with one of those. Just wanted to make sure it would be worth the effort and money. Thanks for the help.