Hi!

I have a XPS 420 running XP SP3. I'm maxed out on system RAM at 3GB.
Core Quad Q660 @ 2.40GHz

I'm very certain the power supply will handle the load. Dell was still using
quality power supplies at the time your system was produced, and they were
conservatively rated. I expect that you'll find at least a 305 watt supply
underhood, and yes, it will be printed on the label when you open the cover.

(In fact, the 305 watt unit I'm used to seeing in various systems really
looks to me like it would be good for 450 watts based on a cursory
examination.)

I have some ATI video cards. They're fine. But as much as I like AMD and
their products, I'm afraid that I'm slightly partial to nVidia. I woud say
that nVidia has a better driver policy, as they tend to support older
chipsets for quite a while and I find their drivers site to be more friendly
than that of ATI/AMD.

William