I assure you going to X64 (IF your hardware supports it) is well worth the money. The performance benefits is outstanding.
I'm trying to run some benchmarks here today (and just got slammed with more work ugh). The first (and only) run I did using Blitz comparing it to MAMEUI's benchs. Considerably lower. Not suprised considering I'm using a 2.83 where as those bench's were like a 3.4ghz proc. Anyway what we're after is the posssibility of IO differences between a 7200 rpm rotational vs an SSD and if so how much. When I get more time I'll post the results.
Can anyone tell me how many cores/threads MAME will actually utilize? I'd love to see how a dual XEON based I7 I have here would fare lol.
Lots of stuff here.
http://forum.arcadecontrols.com/index.php?topic=72776.0

