Windows 2000 SP4 upgrade?

Hi

I was just wondering if anyone had any comments about Windows 2000 SP4. I have a DC, exchange server, file and print server, etc and I was wondering if I should upgrade to SP4. I currently have SP3 on all my servers and they seem to be running fine. I installed SP4 on my test network and it crashed my exchange and file and print server, so is there a particular order I should follow. I looked on different sites for advice and comments about SP4 but I can’t seem to fine any. Please help.