XP updates?

If you run Windows update and select all of the critical updates, you will be up to date.

Service pack 1 included most of the prior updates.

Other updates have been released since then.

Some updates get replaced with newer versions.

Near the end of the summer, Service Pack 2 will be released. This will be a major update.
I recommend that you wait a few weeks after SP2 is released before installing it.
That way, any bugs will be known and have work-arounds posted.

Anyway, be prepared to download around 100MB of updates.

Chas

Currently there are 43 critical updates for windows XP alone. Service pack 1a by itself is 125 megs, and service pack 2 is set to be released mid september. Updates between 1a and 2 are still on the microsoft update site.
To be effective, you should download ALL updates, but if you don't, it doesnt neccesarily mean you are at risk, so long as you protect against the most critical flaws, such as the RPC and LSASS flaws (exploited by blaster and sasser)

If you order Microsoft's FREE Security CDRom you should have it by the time you need it. You can find this CD at:
http://www.microsoft.com/security/protect/cd/order.asp
Personally I wopuld chose the XP Pro version when I got ready to update my OS.

Run the auto update and install all the critical updates. then go through all the optional updates and choose all the recomended ones and any that apply to programs you use