Just wondering which one would be better for me to use. What exactly is the maximum file size for each one? I've heard that there can be issues with ReiserFS V3 when an unexpected power failure (which does happen here from time-to-time) occurs. Also, how good is Windows (XP) support for these partitions? Can Windows read from either/both? write to either/both?

Windows cannot read from either natively, however third-party software allows it to. I cannot comment on the quality of this software.
As for the filesystems themselves, ReiserFS is generally better if you have lots of small files (like a mail server.) I have had to do a hard reboot while the hard drive was going crazy. It messed up the FS, but was nothing a little fsck couldn't fix . If you want something super fast and reliable, you could try out reiser4, but it's not very stable yet. You will also need to build and patch a kernel to enable it.
Hope this helps.

Cheers,
Uman

So on ReiserFS v3 it's unlikely that any irreversable damage would be done in the event of a sudden power loss?

You should be fine. Even so, making regular backups is something that should never be ignored.

Was just looking over some of the benchmarks for Reiser4 and it looks pretty fast. What kind of issues still exist with that FS?

So on ReiserFS v3 it's unlikely that any irreversable damage would be done in the event of a sudden power loss?

Very unlikely, I've turned of my computer more than once without unmounting and I've never had a problem. reirserfsck will check it at boot when it's been uncleanly umnount but it's very fast. I usto use ext3, it is much more likely to get messed up on power loss.

There are benchmarks on the web that compare ext2, ext3, reiserfs, xfs, and jfs. 100 tests or so and reiserfs only lost to ext3 in three or four. In my opinion reiserfs is the best all around fs for linux, without a doubt.

OK sounds like I'm going with one of the Reisers. Basically now, I'm back to the first question only with v3 vs v4.

Reiser is okay, Reiser 4 might be better. Hans is a pain in the bum, but his FS is okay I still prefer ext3 for reasons other than performance tho... Mostly backward compatibility and so forth.

I still prefer ext3 for reasons other than performance tho... Mostly backward compatibility

huh, backwards compatibilty with what? it's a fs, not a program.

backward compatible with ext2...

Backward compatible in that I can boot a tiny distro, or a linux BBC rescue, that only does ext2 and it will still read the ext3 filesystems... There are still a couple that don't come with reiser as a defualt yet, but it's getting better...