I just finished rebuilding my v0.77 roms to v0.36 Final this weekend for a similar reason. I have an old PII Celeron with a TV out card that will be used in a cabinet. It will be classic games only.
Get yourself clrMAME and the v0.36 DATfile from Logiqx's site:
http://www.logiqx.com/Dats/MAMEBeta/MAMEBetaHistory.shtmlUse the Rebuilder and the DATfile to create the v0.36 roms. Once Rebuilder completes, use the scanner to identify missing files (you will find lots of them). These are files that were removed from later Romsets.
Hunting down the missing files is the biggest challenge. I felt like a detective combing old newsgroup postings, sending emails to strangers, etc. If you have access to newsgroups, there's a flood of rollback files being posted to alt.binaries.emulators.mame right now. Rollback files are the files removed from Roms for later versions...they allow you to "rollback" to earlier versions of MAME. Download these to help complete your sets.
There are clrMAME tutorials online. You can find one here:
http://www.mameworld.net/easyemu/clrmameguide.htmclrMAME has a hard learning curve, but is a great tool. It really is super for managing your romsets and fixing any problems.