Hey all, needing a little input on computer upgrading. I haven't been following the latest developments very actively, so would appreciate the feedback.
My current computer isn't bad by any means, but I'm feeling like beefing it up a little. Currently I believe it has an AMD 1.6(or 1.8)ghz dual core processor, Geforce 8800 graphics card, 4gbs of ram, etc. However, I find it still lags in some eye candy games, and now that I happen to have some excess cash(like thats possible

), i want to get rid of those lags!
So bottom line: It's going to be a gaming machine, all the way. I've been thinking I'd hop on the quad-core band wagon, so my first question is, should I go AMD or Intel for the purpose of gaming? I remember ages ago people saying that AMD goes with Geforce, while Intel goes better with the ATI Radeon cards

. Seeing as my current graphics card is a Geforce 8800GTS, should I stick to AMD? Reason I wonder about this is the overclocking possibilities of the Intel Cards..
I suppose I would also have to update my motherboard to house the quad-core processor.
In terms of memory, I believe I have DDR2 ram at the moment, but I read atleast the AMD motherboard requires DDR3 ram, so I'm assuming I'd have to upgrade that as well?
On a final note, what is the actual difference between dual-core and quad-core? No overly technical stuff as that effort will no doubt be lost on me, but in terms of gaming, is there a noticeable improvement? Or should I just consider buying a better dual-core and more RAM, for example? While I'm in the mood for spending money now, if it turns out I waste a ton and end up with very little improvement, I doubt I'd feel very good about myself afterwards.
Thanks in advance people!