I'm considering upgrading but am wondering if its worth it at the moment. My current spec is as follows :

AMD Athlon XP 3000+ Barton (11 x 200)
ASUS A7N8X-E Deluxe 1.01 1008
Seagate Barracuda 7200.7 120GB (SATA)
ATI RADEON 9800 (Flashed to Pro @355/400)
2x256Mb Corsair XMS3200 TwinX 6-2-3-2
SLK-947-U / TT Smartfan II
420w Thermaltake Pure Power PSU

What i'd thought about is the Asus A8N-SLI deluxe with a AMD Athlon 64 3500+ Winchester and i've got a ATI X800 SE 128mb PCI-express gfx card I can pull from another machine.

Would there be a significant increase in games etc with the new mb, cpu and gfx card or would I be aswell keeping what I have and waiting for a few months to see what else new is to come out ?

Take a look at the Alienware computers. I'm thinking of getting one - The Aurora 7500 with harddrive upgrade and the big Nvidia card. www.alienware.com

You'd probably see a bigger boost by kicking the ram up to 1gb depending on the games you run. Without checking some benchmarks I'd say the faster cpu and a slightly faster gpu would certainly increase what you have but I'm not sure if I would say significant.

How much do you have to spend?

May I also recommend the Gigabyte SLI board (ga-k8nxp) which has a few extra features over the Asus board. MSI, Epox, and DFI also have SLI boards, but my personal opinion is that Asus & Gigabyte have the best SLI boards. You can also go with the nForce 4 ultra chip mobo's which cost less and dont have SLI but if your going to upgrade you may as well go SLI. The most costly thing will be the video card but you can always by one now and get another later. You can reuse your hard drive, video card, and PSU and for the time being get new mobo, RAM, and CPU. Later to take advantage of SLI you would have to buy a Nvidea card/s and a higher powered PSU. For instance, if you ran 2 6800 ultra's you would need a 550 wat PSU, and a 480 wat PSU for 2 6800 GT's.

As far as new technology, like the dual core cpu; they will be socket 940 and primarily server application & not gaming etc because of their lower clock speeds. Then the BTX form factor, but thats going to be an intel thing because their cpu's have heat issues, plus they are already selling BTX ready PSU's and cases.

tried the falcon-northwest's computers ? the Mach V configuration just makes you drool.. hehe just wishin I would have those kind of money :S (system I would like: $9,798.80)

I've just decided to keep what I have at the moment and wait maybe another 6 months or so, no point in spending money when what I have is doing a pretty reasonable job as it is !
Thanks for the reply's.