Dell Dimension 2400 problem with increasing RAM

Hard Drive 40G, CPU 2.2G, 512K

Existing RAM is 256. Windows XP Professional. On dial-up.

I contacted Dell to increase RAM.

Dell Sales said should be no problem, just exchange the module.

I purchased a 1G module from Dell and installed it in the same slot, computor starts and displays recognition of the new RAM memory and asks for a choice F1 or F2.

When continueing,  Microsoft warning comes up that it has to shut down and requests error report to be sent.

While the error report is prepared and sent, Microsoft sends back a solution and directs me to a Dell website but because of my slow dial-up, I cannot find out what the solution would be before another warning comes up stating that the computer will be shut down to prevent damage.

Then the computer shuts down displaying a blue page with warnings and technical details and numbers.

What do I need to do to configure the system to the new 1G RAM?

New Dell system driver download? Which one?

BIOS changes? How?

Please, help, I am not very experienced with computer.