Radeon HD 5850 Turbo or Radeon HD 5770 for my x16 slot

I only have 1 PCI express x16 slot and was wondering which card would be better for me...the Radeon HD 5850 (Micro Center - HIS Radeon HD 5850 Turbo iCooler V 1024MB GDDR5 PCIe 2.1 x16 Video Card H585FNT1GDG) or the Radeon HD 5770 (Newegg.com - MSI R5770 Hawk Radeon HD 5770 1GB 128-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card). Would it be worth my money to upgrade to the 5850? I know neither card will perform to its max capability, due to the x16 slot. What specs do i lose due to the lower level slot? Will the 5850 be a better bang for the buck anyways?

Also i have a standard mid tower case...should i be concerned about the space these cards take up or will i be ok?

Thanks!

 

5850, in a heartbeat. But you can get the Radeon HD 6850 for the same price. Go for the 6850.

 

ya that sounds great!...the only down side is my CPU is realllllllllly bad. i have an AMD Athlon X2 3800+ which is a 2.0 Ghz dual core....... i am researching now which would be the best processor to upgrade to since it has the AM2 slot, but i think that it cannot handle the Phenom processors... thats just great...

 

What mb do you have?

 

dell 0RY206 mb

 

i believe this one AMD Athlon X2 3.1 GHz (ADV6000IAA5DO) Processor - eBay (item 270677838622 end time Dec-16-10 17:31:59 PST) or this one AMD Athlon 64 X2 CPU socket AM2 6000+ DUAL-CORE 3.0Ghz - eBay (item 200552494694 end time Dec-14-10 17:00:23 PST) will work. idk tho. i am skeptical to buy a used processor.