Instead of hunting for 32MB cache, try 16MB cache but with NCQ which will order the handling of drive sectors in a logical way that avoids the HD head from moving too much back and forth.
http://www.wikipedia.org/wiki/Native_Command_Queuing
I prefer the Western Digital RE2 series. You don't have to build a RAID setup to to see a performance advantage over regular hard drives.
http://www.hothardware.com/Articles/Western_Digital_Caviar_and_RE2_GreenPower_1TB_Hard_Drives/
Or, try the faster 10000rpm raptors like the raptor X.
http://www.xbitlabs.com/articles/storage/display/wd-raptor-x.html
http://www.wikipedia.org/wiki/Native_Command_Queuing
I prefer the Western Digital RE2 series. You don't have to build a RAID setup to to see a performance advantage over regular hard drives.
http://www.hothardware.com/Articles/Western_Digital_Caviar_and_RE2_GreenPower_1TB_Hard_Drives/
Or, try the faster 10000rpm raptors like the raptor X.
http://www.xbitlabs.com/articles/storage/display/wd-raptor-x.html