[GENERAL] performance tips please

[Hugo]

Hi, I am testing my application and DB (postgres 8.1.4 ) on a :
    DELL-Power Edge 1800 with 2 Xeon 3.2ghz,  2 Gb RAM and 2 SCSI 149 Gb  each.
trouble is that the same application and DB(postgres 8.0.4) runs on a:
     DELL pentium 3 with 526MB of RAM and an IDE 20 GB

and comparing the performance of both, a get only 20-30seconds faster responses on the new server, where can I start looking to find out why is the second server performing this way.

any advice is very appreciated,

thanks in advance

Hugo