Last version I used was 10.1.7xxxx for XP and 10.2.xxxx for Vista. Very stable, no issues here with it.
You can do it in stages, too.
Keep a parent around for the SAV children, and you can setup SEP's manager, SEM, to use the logs from SAV for reporting and to monitor things. You can't update SAV from SEP or the manager, SEM, but you can at least see reports of how many computers have what defs, of infections and so on. SEM will read SAV's reporting. That part is really easy to do.
If you have current maintenance, then you have a legal path to SEP.
Either way, do get into later SAV than 10.1.6 if you stick with SAV for very long. The later builds are safer and better. But if you plan on moving to SEP any time soon, then don't bother........
SEP will catch and do things SAV can't and actually takes less overhead on the client. Do be prepared, depending on the number of client computers and your environment, the manager, SEM, can take some horsepower. We have 370 clients, 2 SEM servers each with 3 gig RAM and 2 processors. 1 processor just didn't cut it - the liveupdate and other processes killed the servers - you could not work on them at certain times, the processors pegged at 80% plus quite often. They are VMWare servers, so I shut 'em down, added a processor, restarted them, let Windows Server2003 detect the change, rebooted again - they are stable as heck now.
Your mileage will vary...........