OK, so, recently I'd been having problems with my mac running a lot slower than usual, so I decided I would format the HD and reinstall everything. The way I formatted, was I loaded up from the os x 10.5.2 disk, went to disk utility, chose the HD with the 'zero all data' option, and clicked erase. it took about 45 minutes to format the 280gb disk, but now that I restarted from the disk again, and chose english, a window pops up and says "Mac OS X cannot be installed on this computer" and the only options are 'OK' or 'Restart' The disks came with the computer when I bought it in August '07. What am I missing? In the installation logs, line 21 says 'Installation checks failed.' Any help would be much appreciated.