I have MAC OSX 10.5.8 and don't know what level of Parallels desktop is compatible. I tried the free download and it will not load with my os. Appreciate and help with this..
If the trial doesn't run neither will the full version. Parallels 8 requires 10.6.8 or later and an Intel Core 2 Duo or better, so no, it won't work on your OS. Unless you have a very good reason to stay in 10.5.8 (which I doubt) you should upgrade to 10.6.8.