Install Windows server 2008 on Dell poweredge 2500

power edge 2500 has Pentium III processor.  are you installing 32bit 2008 or 64 bit.  i would guess that the wcstoul64 is a 64 bit driver.  check to make sure you're installing the correct version of the OS for you hardware

if you are installing windows 2008 64 bit edition those drivers you are using will not work.

It's 32bit 2008

It's highly unlikely that 2008 is going to run on that server. If there's no 2008 drivers I wouldn't even try but you may be able to get it to work as long as the server meets the minimum requirements. Is this R2 or just 2008? With R2 a 2500 will not meet the minimum requirements for hardware.

http://www.microsoft.com/windowsserver2008/en/us/system-requirements.aspx
http://msdn.microsoft.com/en-us/windowsserver/cc196364

It's not R2

What's the CPU speed on it? Is it over 900mhz? I don't recall if that particular model was made with 1ghz or higher chips...every one I ever worked on was a dual 900mhz. 1ghz is the minimum for 2008.

those drivers that youre trying to force to work arent going to work. dell doesnt make the drivers because its not supported. you may be able to find another driver to work, but be prepared for alot of problems. you would be better off finding a raid card that 08 server supports.

Try this driver for the PERC 3/Di.  This is from a PowerEdge 2650, whose hardware is not all that dissimilar from a 25x0 and uses the same RAID controller, and on which 2008 runs just fine:
http://support.dell.com/support/downloads/download.aspx?c=us&cs=04&l=en&s=bsd&releaseid=R192965&SystemID=PWE_FOS_XEO_2650&servicetag=&os=WLHS1&osl=en&deviceid=1375&devlib=0&typecnt=0&vercnt=2&catid=-1&impid=-1&formatcnt=0&libid=35&typeid=-1&dateid=-1&formatid=-1&source=-1&fileid=265517

Remember anything 64-bit is out of the question for this system, since it does not support 64-bit at all.