This is another example of XP being bloatware.
You just DON'T include a program in an OS if you can download a newer version seperately. Not only that, but the XP version is basically a clone of msn messager, and IS NOT msn messenger, so you can have both msn and xp messenger installed, now that can get a little confusing.
Then again, linux is not any better when it comes to that. You'll install red hat 8.0 and it comes with an outdated version of software you can get elsewere but at least with linux you can choose not to install it. Though the package names are usually irrevelent, and some are required for linux to run, so it's hard to no tinclude them