I've installed SP1 and immediately removed it.
[1] SP1 breaks ZoneAlarm - which also prevents you from using IE to access the internet. You have to remove every trace of ZoneAlarm in the registry/hard drive and re-install to get it working again.
[2] SP1 also breaks Netzero. Dialing in works fine, but connecting to Netzero does not. I suspect sp1 breaks any dial-up connection setting.
[3] Win2k takes twice as long to boot up with SP1 installed.
[4] Random lockups lasting anywhere from 5-10 seconds, at least 5 minutes apart. Memory leak issue? Dunno.
I suspect one or all of the above reasons are part of why it's being delayed.