Windows 7: VM disk optimisation using Databases

Hi all
I can't seem to find an answer to this but if I want to use a "transactional" data base system on a Virtual machine is there any way to optimise the Virtual Disk system.

I know that the WHOLE allocation area should be done initially -- allowing Virtual disks to "grow" in the usual manner is a real Death-knell for running any decently sized DB on a virtual machine.

I'm not sure whether I should set the Virtual Disk as SCSI or IDE either -- documentation seems very sparse on this.

Another possible solution is to use "RAW" or "Physical" disks - but these are quite difficult to set up.

I'm trying to set up a SAP IDES system to run on a Windows XP Virtual machine (this application won't run on VISTA or Windows 7) with ORACLE as the underlying DB system.

The Oracle Database system it uses is around 80GB. I've plenty of disk space but any time the Data base Dirctionary is accessed it seems to take a long time. The Virtual machine runs just fine and the SAP system response time is perfectly OK until some DB queries run.

I've already optimised indexes etc etc and the table spaces are fine. I'm sure it's just something in the Virtual I/O subsystem that is causing the problem.

There's around 3.5GB RAM allocated to the VM which is running on a 16 GB RAM QUAD Q9400 processor system -- CPU power and RAM is not an issue.

Any ideas anyone.

Cheers
jimbo