Need some help in choosing a right decision

Hi there, i need some help
right now i have:
CPU AMD Athlon 64 X2 5000+, Socket AM2, 2X512K, bus 2000, 0.09u, 1.4V, 65W, 64bit, (2600 MHz), BOX, Dual CORE, (Windsor)
MB Asus M2N, nForce 430, S-AM2, ATX 24p., PCI-E x16, 3xPCI, 2xPCI-x, Dual DDR2-800, U-DMA 133 S-ATAII Raid 5, SB 6ch.&GBLan on board.. but I don't like how it's working..so i want to upgrade to intel and here i need some help to choosing a right optins with ure help

so here are my options:
MB Gigabyte GA-P35-DS3R, iP35, LGA775, FSB 1333, ATX, 1x PCI-E x16, 3x PCI-E x1, 3xPCI, Dual DDR2-1066, 8xS-ATAII, U-DMA 133, SB 8ch.&GBLan on board

MB Gigabyte GA-P31-DS3L, iP31, LGA775, FSB 1333, ATX, 1xPCI-E x16, 1xPCI-E x4, 2xPCI, Dual DDR2-800, 4xS-ATAII, U-DMA 133, SB 8ch.&Lan on board

CPU Intel Core 2 Duo E6550, 2333 MHz, Socket LGA775, 4096K, bus 1333, 0 065u, BOX, Dual CORE, ( Intel EM64T, VT )
CPU Intel Core 2 Duo E6750, 2666 MHz, Socket LGA775, 4096K, bus 1333, 0 065u, BOX, Dual CORE, ( Intel EM64T, VT )

or should i upgrade my pc with a new cpu like CPU AMD Phenom 9500 Quad Core, Socket AM2, 4096K, bus 3600, 0.65u, 1.1-1.25V, 95W, 64bit (2200 HMz), BOX, Quad CORE, (Agena)

All kind of opinions is wellcome,thanks
(sorry for my poor eng :|)

As of right now I wouldnt recommend a E6xxx if you are gonna go intel. The E8xxx series is already comming out for the nearly the same prices with better performance. I just preordered one and all I gotta do is sit back and wait (its the hardest part).

The E8400 and E8500 are officially not available anywhere until 1/20. Be patient, it's the best way to go.

You will want a P35 based board. A gigabyte board that is at revision 2.1 will support the E8xxx cpu's

Also, get more than 1gb of memory. It is so cheap today that 2gb is a minimum, and I would try to get 4gb.

An os will not use ram that it does not have, it always keeps some in reserve. Vista will use extra ram for performance or something. Also, a program will not use more ram than it has, it does not mean that it would not put more to good use if it could get it.

How bout the Quadcores? I think thats the way to go if you want your build to last a few years. My opinion, Quadcore overclock to 3.4-3.6Ghz, 4GB ram, Vista x64. You should be good to go.

You will max out your dual core when running games along w/ background services.