Whats a better upgrade for Vista Ultimate? CPU or ram? (PC's specs inside)

Hello i recently bought windows vista ultimate for my pc and it seems to be really laggy and maxing out my system so here are my specs

CPU AMD Athlon 64 LE 1600 overclocked to 2.5GHz (socket AM2)

2 Gigs of DDR2 800Mhz Ram

which one would be best to upgrade? Get a dual core Processor or get 2 more gigs of ram?

My opinion: Well it seems to be maxing the processor alot so i think the processor upgrade would be best. i just wanna check with you guys first

CPU, no doubt about it. Cheap X2 5600 or even 5000+ BE would be a welcome addition and make it smooth as butter. I thought LEs were for very low-end systems... Also, if you have lots of RAM, make sure superfetch is on, but disable windows search since it's probably irrelevant for you.Larrymon2000

CPU is not that important if you don't have a lot of RAM. You don't need a lot of RAM if you are running linux but if you're running vista ultimate you need RAM like you need oxygen to breathe. I have a 4GB of RAM and Vista Ultimate and still usage of RAM goes to 90% .

So i think you need to upgrade RAM.