You can download Mac files on a PC. You'll know if it's Mac because it'll have 'for Mac' in the title, and it won't be an .exe file. It can be a bit dodgy - try to download system upgrades etc. on your Mac. I've had problems with OS9 upgrades where the tome is corrupt. Only half the system upgrades, and is incompatible with the other half. I.e. ****ed.

Programs shouldn't be a problem though. You may have to download more than once if it's corrupt, but it doesn't get worse than that.

J