I'd probably suggest you find an experienced DBA as this isn't a simple question to answer. latches are lightweight "locks" and generally not too much to worry about, if lock usage goes high latches usually go high too. You need to read up on sql server waits and locking. as to latches vs disk perf - no not really i guess you're considering waits which show pageio_latch or similar - again you need to understand waits. I've a ms whitepaper for sql 2000 waits on my web site http://www.grumpyolddba.co.uk - go to the sql 2000 page.

I usually find SAN's to be a sql bottleneck as most vendors/admins don't understand sql server io requirements. Basically most production sql servers need dedicated spindles ( no shared luns - at all ) and raid 10 / raid 1 any other raid is only useful for a read only database. Check partition allignment - there's some posts about this elsewhere on this section. use windows disk io completion time to check if you've got problems - block sizes on format and queue/buffer depth for HBA's will also help/hinder depending upon settings.