> [Old]

>

Server 2003 x86 no service packs

>

Xeon with 4 GB RAM

>

Classic 1.5.4 (x86, of course)

>

Raid 0 on 2 * 500 GB SAS (though this is from memory, I should look it up...)

>
>

[new]

>

Server 2008 R2 x64 SP1

>

Xeon with 8 GB RAM (I will shortly add +8)

>

Classic 2.5.3 x64

>

Raid 0 on 3 * 600 GB SAS

  Raid 0 ? Are you sure ?

> In comparison to what I read from others, my databases are small.
> Biggest database is some 1 GB only.

  Agree, it is small database.

>

Bad performance on updates and inserts and extremely bad performance

>

on committing a big number of record changes (~ 150.000 updates).

  It points us to the issues with writes or with random writes. It could be interesting
to see results of disk IO benchmark (any you like which able to test random writes).
Also it is good to know some raid settings such as stripe\block size, write cache mode,
presence of BBU (battery for internal cache).