Why did you install Adobe Audition twice?
Seriously though, check Matrox's web site for the list of compatible h/w and it's configurations. Also, as you have the s/w already, you'll effectively be buying it again. There was a some talk a while ago about Matrox releasing a h/w only option so you'll not have to buy s/w you already have. Investigate that also.
You really do have to be careful (from all the anecdotes) to get a compatible system. Apparently the thing is even fussy about which PCI slot it goes into! It's also a sizable investment for most as well. But, speaking personally, the lack waiting to render time has already saved me over a week (I reckon) so it soon pays for itself in these terms.
Also, marc does have a point about new s/w not being compatible. Anecdotal evidence would indicates that the most stable platform for the card is Premiere 6.5. Each version brings more and more issues for more and more poeple. However, the good news though, is that Adobe do listen to RTX100 users. The latest upgrade (patch) to Premiere (1.5.1) has code changes to support (fix issues for) the RTX100 purely as 'a favour' to Matrox.