I bought this XPS 420 in May 2008, and frankly, its been a very reliable system.  I've replaced the drive, added a second optical drive and a second hard disk, upgraded the RAM to 8GB, and replaced the 8800GT with a 9800GT.  Its running 64bit Windows 7 Ultimate without a single problem.

I thought I would try setting it up to use a SSD (Patriot Inferno 120GB) as its primary boot device, and upgrade the video card to a GeForce GTX 460.

The system won't boot with 5 SATA devices, its extremely underpowered.

The stock PSU only has one 6pin PCI-e connector, so the GTX 460 cannot be used.

Thankfully the PSU is standard, and can be replaced with a unit that supports the hardware I want to use.

The ICH9R Sata controller firmware is seriously old.

The A07 Bios was released by Dell in May 2009.  It has PCI Option Rom for ICH9R version 7.6.1.1001

Intel has revised their own X38 Express chipset motherboards with the ICH9R controller 4 times since October of 2008:

October 9, 2008
SATA RAID info:
Intel(R) RAID for SATA - v7.6.0.1011
January 28, 2009
SATA RAID info:
Intel(R) RAID for SATA – v8.6.0.1007
July 1, 2009
SATA RAID info:
Intel(R) RAID for SATA – v8.9.0.1023
October 23, 2009
SATA RAID info:
Intel(R) RAID for SATA – v8.9.0.1023

The release notes for January 2009 specifically indicate that it was to support SSD's.  Internet searches for this issue have show that other systemboard manufacturers have had to revise the ICH9R controller firmware for exactly the same reason, SSD support. 

Why has Dell not revised the ICH9R firmware?  I've been told by XPS technical support that Dell is dependent on the manufacturer to release updates, which clearly they have.  It would be nice if Dell engineering or XPS brand management would take the 10 minutes or so to replace the PCI Option Rom in the XPS420_A07 (and other makes/models) for the ICH9R to upgrade it to 8.9.0.1023, or release the tools so we can do it ourselves.

I know there is room in the bios for a newer ROM, as hex editors show lots of empty space at the end of that module.

I've made 3 phone calls to Dell on this issue, scoured the internet for forums on how to mod the bios myself (pretty much every BIOS can be modded easily, EXCEPT DELL) with zero results.

If you look at other models with the same SATA Raid controller (ICH9R) that Dell has sold, not a single one of them has had a revision past 7.6.1.1001, which is more than 2 years out of date.