Problem with XP Pro x64 Edition

Long story short, I decided I'd like to try the x64 edition to use > 3GB of memory on my XPS720, which I anticipated as a fairly straightforward task. Not so, my brick wall was installing the nVidia SATA drivers. I downloaded and tried the most recent drivers from Dell, but I couldn't get them installed at all. The Dell instructions say:

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Hard Drive Installation (via WinZip) with HTML Pop-Up Window for
R164976.EXE

Download
1.Click Download Now, to download the file.
2.When the File Download window appears, click Save this program to
disk (Windows XP users, click Save) and click OK. The Save In: window
appears.
3.From the Save In: field, click the down arrow then click to
select Desktop and click Save. The file will download to your desktop.
4.If the Download Complete window appears, click Close. The file
name icon appears on your desktop.

Install
1.Double-click the new icon on the desktop labeled R164976.EXE.
The Self-Extractor window appears.
2.Click OK or Continue.
The Self-Extracting Driver Installation window appears and prompts to
extract files to C:\DELL\DRIVERS\R164976.
3.Leave all of the default settings and click Unzip or OK. If the
directory doesn't exist, you'll be prompted to create one. Click Yes. A
Self Extractor window appears and indicates C:\DELL\DRIVERS\R164976 files were
extracted.
4.Click OK.
Follow the on-screen installation instructions in the window.

HTML Pop-Up With Install Now Button
1.The Dell Software Installation Documentation window appears.
2.Click the Install Now button. A File Download window appears.
3.Click Run this program from its current location and click OK.
The Security Warning window appears.
4.Click Yes. The InstallShield Wizard window appears.
5.Follow the on-screen instructions.

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I downloaded and ran the package in the usual fashion, but there were no "on-screen installation instructions" to follow, just a screen s howing the extracted files, nor was there an "HTML Pop-Up With Install Now Button". I tried creating a floppy with the Dell drivers, but Windows Setup rejected them saying there was no "txtsetup.oem" file. I downloaded nVidia's latest drivers from their site and extracted the drivers. I created a floppy with the files from the sataraid folder and these worked fine with the C: & D: drives. However, I had no access to my E:, F: & G: drives (they showed as "unknown" instead of "basic" in XP's Disk Management display). The drives were fine in my XPS410, so I tried unloading the data from the HDD and redefining it under x64, but that failed as well). I tried examing the HDD with PartitionMagic, which gave me a Sector #48 Sector Not Found error. At this point I gave up and restored the 32-bit version of XP Pro and all was well, of course, all HDDs intact & solid.

I bought & installed 8GB of Corsair memory 4 x 2048MB, which never caused so much as a blip and which is still in the 720 running the 32-bit version of XP.

Finally, the Dell instructions assume downloading & installing the drivers from a running system, but how am I supposed to perform the initial install? I need a floppy with drivers, otherwise Setup says it can't find any disks drives & terminates. The nVidia drivers are version xxx.691, while the Dell drivers are version xxx.699, so I assume there's something new & required in the Dell drivers. The extracted file names aren't the same, so I couldn't try fudging the install that way.

Any suggestions/advice greatly appreciated.

TIA

http://support.dell.com/support/downloads/download.aspx?c=us&l=en&s=gen&releaseid=R164976&SystemID=XPS_720&servicetag=&os=WXPX&osl=en&deviceid=9711&devlib=0&typecnt=0&vercnt=1&catid=-1&impid=-1&formatcnt=1&libid=41&fileid=221849
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