Not encountered this model, but have 'upgraded' numerous HP/Compaq models,
and so far not one has beaten me. Some might involve a bit of head-scratching
over deciding on the right drivers to use, etc. but all of the drivers should
be available.
I note that
http://www.hp.com offers no XP drivers for this model, but you
may find that nVidia supply drivers for the main chipset.
Since it's an nVidia chipset I suspect you won't have any problem with
IDE/SATA boot-time drivers, but if you find the XP setup won't run, check the
BIOS settings for a SATA mode option, and set it to 'IDE' or 'Legacy' mode.
Before you format the HD (which is essential) take a look in Vista's Device
Manager and note down the IDE/SATA, display, modem and sound driver types.
This will save you some hassle later.
As for warranty, IMHO the other comments are nonsense. Vendors know that
users will install software, and that they cannot deny them the right to do
so. How does replacing the OS differ from installing a game that bluescreens
the computer, necessitating warranty support?
In any event, most business users would erase the HD when returning a
computer as U/S under warranty. Again, most vendors realise that this is
necessary to protect the company's data.
As for the performance advantage; like night and day. Especially as you will
be getting rid of Norton, which is even more of a performance-hit than Vista.
Use Avira, AVG or Eset AV instead.
The other option, I suppose, is to wait for Windows 7, which from the betas
looks to be a vast improvement over Vista. You would still want to do a clean
install, though, especially on a Nortonised computer.