XPS upgrades

Ok, so i have read that i could go to 64 bit but not sure if my microsoft office etc would still work ? if i go to 64 bit can i go to 8Gb memory ? Also is my board capable of running a faster chip.

Thanks for any help / advice. much appreciated.

Yes, if you install a 64bit OS, it will address all 8GB of RAM.

What processor do you currently have?
Here's a list of compatible processors for the XPS 420. Dell might have a more recent list.

XPS 420 Processors:
--------------------
QX9650
QX6850
QX6800
QX6700
Q9450
Q9300
Q6700
Q6600
E8500
E8400
E6850
E6750
E6550
E6420
E6320
E4400
E4300

Yes, Office 2003, 2007 and some of the earlier Office products will run on a 64bit platform.
Here is what I'm running on 64bit Vista Home Premium. All I did was go to the software vendor's site to check 64bit compatibility and in some cases simply installed the software and it ran fine.

Canon MP460 Printer                    (download the Vista 64bit drive)
nVidia driver                                 (download the Vista 64bit driver)
RivaTuner v2.11 or above            (runs on 64bit Vista)
Acronis True Image 10 and 2009 (runs on 64bit Vista)
NOD32                                          (download the 64bit version eav_nt64_enu.msi)
Nero 8                                          (runs on 64bit Vista - needs MS XML core services (MSXML) 4.0 sp2 installed)
MS Money Plus                             (runs on 64bit Vista)
Intel Matrix Storage Manager      (runs on 64bit Vista)
Logmein                                       (runs on 64bit Vista)
Citrix Client                                  (runs on 64bit Vista)
Office 2003                                  (runs on 64bit Vista)
iTunes v8                                    (download the Vista 64bit version)
AIM v6                                        (runs on 64bit Vista)
Virtual PC 2007                          (download the Vista 64bit version)
Foxit Reader                              (runs on 64bit Vista and opens PDF files from 64bit IE)
Yahoo IM                                   (runs on 64bit Vista)
WS_FTP Home v9.01                 (runs on 64bit Vista)
Quicktime                                  (runs on 64bit Vista)
COD4                                         (runs on 64bit Vista)
Teamspeak                                (runs on 64bit Vista)
MS Frontpage Express 2.0        (runs on 64bit Vista - after install, Run As Administrator)

can i switch to xp pro from vista on my xps 720??

Also the system is not capable of SLI as you have only one x16 PCIe slot

can i switch to xp pro from vista on my xps 720??

you should really start a new thread. It is considered bad forum etiquette to jump onto another s thread.

But to answer your question yes you can I did. But you will have to do a clean install. And windows 7 will also work on a 720