Time Machine Backup Drive ?

Does the external drive you use for your Time Machine backup have to be dedicated strictly for Time Machine or can you use any external drive that has enough free space on it?

You can store other data on the same partition that Time Machine uses for it's backups. Most folks do not recommend doing it - however, I have been using a single partition for TM backups from multiple Macs along with other data on it for over 3 years that I really started as an experiment. However, I also maintain bootable cloned backups for my Macs separate from the TM drive.

So, you can use any external drive that has enough free space - as long as that partition is formatted as HFS+.
You want to use some drive that you're bringing over from your Windows machine and directly connect it to your Mac that's formatted as NTFS or FAT32 - not gonna happen without reformatting. I'd recommend you go spend the $50-$70 for another drive.

Thanks Bob....I forgot about the formating issue!