virtualbox.org

I have an old PC as server with Windows 2003 Server installed.
Its a little shaky and has only one IDE disc, 512 MB Ram etc...

I just purchased a real server machine that also has Windows 2003 server installed.
I was thinking that instead of merging it all over to that one, just install VirtualBox and clone the old disc.

Will this be possible ?

I have never cloned a installation in to a VirtualBox before, only made fresh installs.
How do I proceed ? (Guide?)

Discussed many times. Image the (entire) original disk with Disk2VHD, convert the VHD to VDI using CloneVDI or VBoxManage, then build a VM around the VDI. Try to end up with the VDI inside the VM folder, otherwise you are creating problems for the future.