Memory for a Dell 2400

Hi,

Forgive a stupid question, but I know I'll find experts here and don't want to hold an hour for "Dell India Tech Support" that I can't understand. :-(

My father, who lives a couple of hours away is a computer novice, but said he is having speed problems with his computer. He uses it for the web and basic software, but it's slow as can be. Well, I have discovered via walking him through Windows that he only has 256 MB of RAM and I suspect that to be his major problem when running Windows XP.

According to the "System" tab on his maching, he has a "Dell Dimension DIM2400" that is running a Pentium 4 2.53GHz CPU. So, the processor doesn't seem to be at issue.

I BELIEVE from the reading I have done that his machine can take up to 1GB of memory and has two memory slots inside. However, I can't run up there a few hours to check and he has never opened a PC before so I don't want to attempt that via phone.

I plan to buy him 1GB of memory (two 512MB memory), remove the 256 and upgrade him to 1GB which should solve his problem. However, I am not sure what type of memory the machine takes and really don't want to buy something and drive two hours to find out I have the wrong stuff. He lives in an area with no electronics retailers (very rural) so if I showed up with the wrong stuff, it would be a mess to drive back and forth.

Does anyone know for sure what type of memory this box takes? The max?

I would appreciate any help so I can make one trip to him and get the job done.

Thanks!