The CPU upgrade I installed was not something from the Dell website.
You can replace the CPU with a T7600, and upgrade the BIOS to the
latest, and you will then have a 64 bit
machine that will run any 64-bit Windows OS and any 64-bit Linux OS. I
have PCLinuxOS KDE 64-bit on it right now. I have seen some reference
to adding something to the BIOS
that would enable the entire 4 GiB ram, but I have not done that. With
4 GiB installed, you can use 3.2 GiB. You should be aware that the
WIFI chip is Broadcom, and it will run
without a problem in Windows and in Mint 17 Linux, but will give you
fits to get working in PCLOS, altho it can be done. You can also
change the small HD to a larger SSD.
Whether or not this is all economically worth while, or you should
throw the machine out and buy a new one is up to you.