Windows Update necessity question

I'm currently running Windows XP Pro with SP2. I have the automatic updating of the operating system enabled, and it updates itself periodically. My question is: from SP2 and afterward (ie. the updates that were released after SP2), how necessary are the updates? Should I disable them? What disadvantages would this pose?
I ask because I recently wiped my hard drive, and notice that it takes longer to start up, and even longer to shut down after it downloads these updates. I cannot say for certain whether the updates are the problem but I have a good feeling that they are.

Any thoughts?

 

usually the slow downs are more a result of minor problems in windows and its registry piling on top of each others day after day.

I formated 2 days ago, and then applied all the updates. I noticed no speed loss from doing so. Just make sure to defragment your harddrive after you apply them, cause on installation they do tend to cause quite a bit of fragmentation.

These updates are mostly to fix security problems that were recently discovered. So not having them might increase your risk of having security problems.

 

I turn off the Windows Update. It is very annoying. I'd suggest a good firewall and virus program. I only update with service packs. If you go this route I'd suggest a good backup.