Maximum Possible Insert Performance?

My situation is this. We have a semi-production server where we 
pre-process data and then upload the finished data to our production 
servers. We need the fastest possible write performance. Having the DB 
go corrupt due to power loss/OS crash is acceptable because we can 
always restore from last night and re-run everything that was done since 
then.

I already have fsync off. Short of buying more hardware -- which I will 
probably do anyways once I figure out whether I need more CPU, memory or 
disk -- what else can I do to max out the speed? Operation mix is about 
50% select, 40% insert, 10% update.