I've just bought a mac mini (intel duo core). I'm still getting used to it but i think i'm about there. I have just also bought a hard drive caddy for my old windows pc hard drive so i can transfer the files then use it as an external hard drive. how can i format the old hard drive so it's totally blank (if i try to delete files using finder it says loads of files are blocked) I just want to totally blank it now my files are transfered. Thanks. (btw i dont have a windows machine anymore so its not possible to format it using that)

Put it in the caddy, connect it to the Mac and format it?

In finder, Go>Utilities (or Shift+apple+U), opens the utilities folder. Open disk utility. If the Hdd is on and connected it will show in the disk list. Select and choose Erase or Partition.

Thanks Hade will do that tomorrow.