I have a rather old Intel Celeron 2,35 ghz cpu with (from what i can tell with cpu-id) an Intel 82801 chipset. It was bought from Dell 5 years ago.
I would like to upgrade to a Intel-VT capable processor. Is this possible?
82801 is a southbridge not the chipset
I think given the age and socket it is probably a Prescott Celeron D which would be an 845 or 865 chipset. Which limits your upgrade options to the old Pentium 4. It predates VT extentions by a long time so it would not be at all possible to upgrade to a VT enabled CPU and isn't really worth upgrading.
Really you are looking at replacing the machine. There may be components that you can bring across like the harddrive but to think about a cpu upgrade you really need a motherboard which is 2 years or less.
List of celerons with dates, sockets and chipsets http://en.wikipedia.org/wiki/Celeron#Celeron_D
CPU upgrade might or not be possible, but I counsel against, as too many other components in your computer will not be able to keep up with the performance of the new CPU.
I rather suggest investing in a a new computer, as prices have also gone down quite a lot since 5 years ago.
IF your board features an LGA 775 socket anf IF the BIOS supports VT-x (which i doubt with a 5 years old DELL), then you can upgrade to a VT-x capable processor.
there are two Pentium 4 HT processor that are VT-x capable and that will fit the LGA 775 socket:
Pentium 4 HT 662 3.6 GHz
and
Pentium 4 HT 672 3.8 GHz
but to be honest, this isn't worth it. buy a new machine if you want VT-x powered virtualization.
Intel-VT requires BIOS support as well as CPU support. Just becuase you can get a CPU that includes VT that will fit your board, don't assume that it will either work at all, or give you VT support. There may be a new BIOS available for your board that provides support for newer CPU's and/or intel VT. (You might be lucky and it is already included).
There are old P4s that include VT, finding one might be hard though. Especially as it was not a standard feature back then. If you look here it will tell you wich CPU's include VT.
You also need to keep in mind that if you go from a Celeron to a P4, that is more power that the board needs to be able to deliver. It may or may not be capable of it.
I am assuming that you intend to run several virtual machines on this system, as you are after VT. :) The best CPU you are likely to be able to fit is some form of P4, as your board is probably too old to accept a Core 2. I don't think the performance of that is going to be very good for virtualised workloads. I therefore also have to suggest that you go look at new hardware, it will be much less hassle, and will perform much better.