pgbench results on a new server

I've got a new server and want to make sure it's running well.  Are these pretty decent numbers?

8 cores (2x4 Intel Nehalem 2 GHz)
12 GB memory
12 x 7200 SATA 500 GB disks
3WARE 9650SE-12ML RAID controller with BBU
   WAL on ext2, 2 disks: RAID1 500GB, blocksize=4096
   Database on ext4, 8 disks: RAID10 2TB, stripe size 64K, blocksize=4096
Ubuntu 10.04 LTS (Lucid)
Postgres 8.4.4

pgbench -i -s 100 -U test
pgbench -c 5 -t 20000 -U test
tps = 4903
pgbench -c 10 -t 10000 -U test
tps = 4070
pgbench -c20 -t 5000 -U test
tps = 5789
pgbench -c30 -t 3333 -U test
tps = 6961
pgbench -c40 -t 2500 -U test
tps = 2945

Thanks,
Craig