Hey there new poster here so please be gentle 
I built my computer in 2004 with all parts purchased from Overclockers and intend to upgrade with all Overclockers purchased parts..
Anyway my 5 years old system is having trouble playing a lot of games like Warhammer Online/LOTR Online and Age of Conan and Ive tried to stretch this system as far as it can go but I think ive gone as far as I can with it..
But I need some advice im a bit confused about, Im not a computer builder at all I just know how to read instructions and put things together...
I have: Asus A8N-Sli Premium Motherboard and It says it can support AMD Athlon 64 and of course I already have a AMD 64 already installed which is a 3500 version at 2.21 ghz which really isn't stepping up to the mark where gaming is concerned anyway Ive been looking around the internet trying to find this out but can I use Dual Core with this motherboard? Something like : http://www.overclockers.co.uk/showproduct.php?prodid=CP-246-AM&groupid=701&catid=6&subcat=803
And also am I restricted to what Graphics card I can use in said motherboard?
for example can I use this : http://www.overclockers.co.uk/showproduct.php?prodid=GX-176-AS&groupid=701&catid=56&subcat=1009
The Motherboard manual says it suports Sli but im not sure if it would support any kind of graphics card it doesn't say that in there..
Anyway sorry if these questions seem totally dumb to you I just wanted some pro advise before I can and spend the money, Thanks for all replys in advance.
++ Here are my Motherboards full specs, I didnt want to copy paste because its a bit much : http://www.ngohq.com/home.php?page=articles&go=read&arc_id=34

I built my computer in 2004 with all parts purchased from Overclockers and intend to upgrade with all Overclockers purchased parts..
Anyway my 5 years old system is having trouble playing a lot of games like Warhammer Online/LOTR Online and Age of Conan and Ive tried to stretch this system as far as it can go but I think ive gone as far as I can with it..
But I need some advice im a bit confused about, Im not a computer builder at all I just know how to read instructions and put things together...
I have: Asus A8N-Sli Premium Motherboard and It says it can support AMD Athlon 64 and of course I already have a AMD 64 already installed which is a 3500 version at 2.21 ghz which really isn't stepping up to the mark where gaming is concerned anyway Ive been looking around the internet trying to find this out but can I use Dual Core with this motherboard? Something like : http://www.overclockers.co.uk/showproduct.php?prodid=CP-246-AM&groupid=701&catid=6&subcat=803
And also am I restricted to what Graphics card I can use in said motherboard?
for example can I use this : http://www.overclockers.co.uk/showproduct.php?prodid=GX-176-AS&groupid=701&catid=56&subcat=1009
The Motherboard manual says it suports Sli but im not sure if it would support any kind of graphics card it doesn't say that in there..
Anyway sorry if these questions seem totally dumb to you I just wanted some pro advise before I can and spend the money, Thanks for all replys in advance.
++ Here are my Motherboards full specs, I didnt want to copy paste because its a bit much : http://www.ngohq.com/home.php?page=articles&go=read&arc_id=34