There are several threads asking about windows 8 and the general consensus is that generally it works better than previous versions of windows
It isn't windows 8.
A couple of things to think about...
What graphics card does your desktop have and what drivers have you got installed?
Have you tried temporarily disabling your antivirus/firewall to see if that makes a difference?
What are the specs of your desktop?
My stuff is
CPU- AMD A10-4600 APU
Ram- 5.6 GB
Video Card- AMD Radeon HD 7660G
All this stuff shows up as allowing me to run SWTOR on the "Can I run this" sites. The only thing it ever questions is my OS being Windows 8.
I have tried taking down my firewall to no avail