Issues Installing windows xp 64 bit on dell t7500

Go to Dell drivers and download the sata driver. During the install press f6 when prompted to install sata or raid drivers. Load the sata drivers and raid drivers then continue with the install. it ??Should?? work.

If not, set your windows 7 machine for multiboot and install XP 64 from windows 7.

Failing that contact Dell and tell them that you want a replacement drive with XP 64 pre-installed. They will tell you that they can't until you tell them that you are sending the machine back.

Pray tell - what would run in XP 64-bit that will not run in Windows 7 64-bit?

My first foray into 64-bit was with Vista Business and the only piece of software on that machine that would not run in Windows 7 Pro 64-bit was my VPN application. I replaced it with a better VPN application and moved on.

What do you need to run that won't?

... Thinkpads_User

Im with thinkpads_user. 64-bit 7 has much better driver and app support 64-bit XP. 64-bit XP was short lived so very few drivers were fully developed. If you have an app that absolutely needs xp, why not use windows 7's XP mode?
http://arstechnica.com/microsoft/reviews/2010/01/windows-xp-mode.ars
http://www.microsoft.com/windows/virtual-pc/download.aspx

The issue is my new customer is still running on NT 4.0 PDC which is NOT going to change for a few months. The new Windows 7 will not join the NT domain so I am trying to putting the XP 64bit (64 Bit required for a CAD program)

While I agree with the others that there is likely no need to install XP (for 1. Compatability is great, and 2. you can run XP Mode - from Professional, Enterprise, Ultimate - for most other issues), here is what you need to do if you are hell-bent on installing XP:

You said LSI/SAS controller ... there are actually two that could have been configured with it:

SAS 6/iR:
http://support.dell.com/support/downloads/download.aspx?c=us&cs=08W&l=en&s=bsdv&releaseid=R193680&SystemID=PREC_T7500&servicetag=&os=WXPX&osl=en&deviceid=14266&devlib=0&typecnt=0&vercnt=1&catid=-1&impid=-1&formatcnt=0&libid=46&typeid=-1&dateid=-1&formatid=-1&source=-1&fileid=267108

PERC 6/i:
http://support.dell.com/support/downloads/download.aspx?c=us&cs=08W&l=en&s=bsdv&releaseid=R211427&SystemID=PREC_T7500&servicetag=&os=WXPX&osl=en&deviceid=13854&devlib=0&typecnt=0&vercnt=2&catid=-1&impid=-1&formatcnt=0&libid=46&typeid=-1&dateid=-1&formatid=-1&source=-1&fileid=297706

You will need to put these on floppy and load at the F6 prompt during Windows setup.  Alternatively, you can use nLiteOS.com to integrate the drivers into the installation media.

Did you try to change the HDD mode in BIOS to IDE compatible?

PowerEdgeTech:
Tried both drivers with f6 and nLiteOS and still blue screens. XP 32 bit loads fine and XP 64 blue screens

>>> The issue is my new customer is still running on NT 4.0 PDC which is NOT going to change for a few months.

You might consider an off-domain approach:  In the Windows 7 Pro machine (I assume you may be able to try this), set it up as WORKGROUP and not Domain. Make a batch file to connect to the NT4 server shares it needs to. Test to see if it works.  If it does, you can put this file on the desktop and ask the user to double click on it when starting up in the morning.

The batch file would have lines such as: NET USE Z: \\NT4SERVER\usershare /user:userid password

It is a workaround in the situation, but the user will have all the services they need. When some newer server comes in in a few months, you need only join the Windows 7 PC to the domain.

... Thinkpads_User

This might be a hardware problem (RAM or CPU). How much RAM do you have installed? Run a memory test and check if you get any errors. You can use MEMTEST86 for this. A good tool for diagnosing problems is the Ultimate Boot CD (UBCD). Download it and burn the ISO to CD and boot from it. From there you can run memory and CPU diagnostics.