We're planning to change our server and porting actual DBMS Interbase 6.01 to Firebirds 2.1.1.
So, we've to decide which hardware and O.S to buy, these our possibilities:

CPU: 2 Xeon QC
RAM: 4GB ram
HD: RAID10 100GBx6 SAS
SO: Windows Server2003 32bit

CPU: 2 Xeon QC
RAM: 16GB ram
HD: RAID10 100GBx6 SAS
SO: Windows Server2008 64bit

In your opionion, which configuration could be better, in terms of perfomance?
Firebirds has some limitations or execution problems choosing 64bit operating system?

Thank's in advance...