external HD- format /partition ??

Shopping for a hard drive for backup. I see some come formatted for Mac others have to be reformatted. I see terms like FAT32, NFSA, etc. As a novice user, should I get an already mac ready unit? I do have a Windows laptop, which may share files.

A related question...what is partitioning a drive? Do I need to do that?

I essentially want the backup to handle music, pics, and the like. Also for the time machine function with Leopard.

OK, here's how it is.

Mac OS X works best with a format called Mac OS Extended (Journaled). This is the quickest, safest and most efficient format. However, it only really works with Macs (OS X).

FAT32 is the old Windows format (Win95, Win98). It also works quite well with Win XP, Win 2K and can be read by almost any OS, including OS X and Linux. FAT32 has two big drawbacks though. Firstly, you cannot have partitions greater than 32GB. Probably not a problem in 1997, but now a bit of a drawback. Secondly, it has virtually no security, so data on a FAT32 drive is difficult to protect.

NTFS is the Windows NT File system, most commonly seen on XP and Vista machines. It's a lot more secure than FAT32 and allows much larger partitions. It can (sometimes) be read by OS X and other non-NT based operating systems, but they cannot write to it. Some software claims to get around this, but frankly that's quite recent and not reliable, IMO.

So... If you buy a huge external HDD, here's what I'd do. Create two FAT32 partitions of 32GB each to share data with Windows, back up your Windows machine and backup generic files you may one day wish to restore to a Windows or Linux PC.

Format the rest as Mac OS Extended, and use this exclusively to back up your Mac and put files in cold storage. Use Disk Utility to do this.