I realize the Dell PE2500 is not on the "supported" list, though I'm wondering if anyone has successfully installed ESXi. I'm going to attempt it myself if I don't hear anything within the next week or so and will report my results.
I haven't seen anyone, but other PEs have been fine - http://www.vm-help.com/Whitebox_HCL.php. The main thing is the storage controller and NICs - do you know the specfic models that your system has?
The PERC 3/Di is a supported controller - http://www.vmware.com/pdf/vi35_io_guide.pdf and you'll likely be fine with the NICs.
Thanks for your help, Dave. I can now confirm everything works fine with my Dell PE2500. This is a dual 1400MHz (PIII) server using a PERC 3/Di. The PS/2 keyboard is picked up properly throughout the setup and on the console. After entering the license key, I did have to reboot the server once in order to pick up the 2nd processor as licensed.
I've got ESXi 3.5 update 3 running on my PowerEdge 2500SC.
I have a PERC 3/Di which didn't work initially but after hearing that it could be done I updated the firmware from 2.5.0 to 2.8.1 and then the ESXi installer was able to see the logical drive.
The processors, which are 1.0GHz Xeons, detect on the console as "AABC" and within the VI client as "%01%01%02%03" but it still seems to be working OK.
Thanks!