Eric Sloof inspired me with his blogpost about the whitebox he is using (http://www.ntpro.nl/blog/archives/866-My-ESX-future-version-compatible-WhiteBox.html). After reading his posts I wanted to see if my HP ML 110 G5 is also compatible with the next version. And Yes it is! :-D.
In fact everything worked out of the box. Storage (onboard Sata controller), Onboard NIC and the DVD-Rom.
More info about the HP ML110 G5 can be found in this post: https://ict-freak.nl/2008/08/04/hardware-hp-ml110-g5-x3065/