I need to share files between Mac, Windows XP and Linux. I have a spare 120Gb SATA 2.5 drive in a caddy that I'm hoping I can reformat (it was damaged when I dropped my Macbook but I can read files from it OK)

FAT32 seems like the obvious candidate, although there is the 4Gb file size restriction which would be a problem as I'd like to store movies on it

NTFS is readable and writeable by Windows and Linux, but not sure if OSX will write to it.

HFS+ isn't supported by Windows, nor is EXT3 or ReiserFS

Why isn't there a suitable filesystem that one can use across all types? Seems crazy to me...

As far as I know, Mac OS X will read NTFS, but will not write to it.

You could partition the drive into two and have one big NTFS partition and perhaps a handful of FAT32 partitions.

If you have a large file on your Mac that you want you share with Windows or Linux, write it to a FAT32 partition, then in Windows (or Linux) move it to the NTFS partition where it can be read by all. You won't be changing movie files, so no need for Write access from the Mac.

Sure, it's not as simple as a single partition for everything, but it might be good enough to do what you need.

Whilst you can write to an NTFS partition from both Mac and Linux (with the correct free software), you are advised not to. Noone but MS and those who've seen the source code and APIs truly know how NTFS works, so as good as the open source implementation is, guesswork still exists within it. Sure, it'll probably work fine and you'll have no problems, but the potential exists for something to go horribly wrong.

You can read/write HFS+ on Windows using MacDrive, and there is a read/write driver available for Linux. That said, the same caveats apply as per NTFS.

FAT32 is tried and tested on all of them, so you need really to decide whether you're prepared to put up with a) file-size limits, or b) the possibility of problems arising from using reverse-engineered filesystem drivers.