Pg+Linux swap use

Hi,

Old: Post 7.3.2, P4 1.8, 1 MB RAM, 2 x IDE SW RAID 1, RedHat 8
New: Post 7.3.4, Xeon 2.4, 1 MB RAM, 2 x SCSI 15k SW RAID 1, RedHat 9

Both use: Only postgresql on server. Buffers = 8192, effective cache = 100000

In old plataform the free and vmstat reports no use of swap.
In new, the swap is in constant use (40-100 MB), with a low but constant
swap out and swap in. The cache memory ~ 830000 and buffers ~ 43000

I try to reduce the buffers to 1024 with no effects.

Thanks,

Alexandre