I’ve been thrashing openSuSE (and in x64) off and on for the past couple of years, and recently got myself (for now) a Q6600 to throw at it (the Q6600 will eventually go to my Mom for a Christmas present when I get my i5-2500K build finished) - in the meantime I threw 12.1 (x64 of course) at it to see how much a performance gain it would have over the CPU it replaced (E3400). The CPU is, in fact, the only change, therefore hardware compatibility was not an issue. One change I DID make from my usual test setup was the file-system choice - I went with btrfs, not ext4.
Jeepers, creepers, the install almost outran my peepers.
Twenty minutes, all told - including not only the system configuration, but the first set of updates (128 files).
Well, I did throw it at a i7 2600K which screens, but I want to say I too have a Q6600 and it works like a champ with openSUSE 12.1. The installation is by far the fastest I have seen in a while. I don’t spend much time configuring openSUSE since I know it so well which might take longer with others but you just know that the i5 2500K is going to be faster than a Q6600 unless there is some sort of disparaging difference in the hard drives being used. You should be very happy with its performance.