Max amount of RAM?

You are correct the max is 2GB.

Although your motherboard is a 32 bit highway the address lines to the memory will only address. 2GB ie 1GB per slot

Ugghhh Pentium 4 system. I seen the motherboard for this there is only 2 slots and the max size you can put in it is 1GB per slot. You want my advice I would just scrap that system since the Pentium 4 systems were not very good. They can barely do facebook these days. It does not matter if you put in a gaming video card the Pentium 4 it is 15 years old. You can buy Duo core system or better or find them on the curbside that will do circles around that Pentium 4 system. I would not waste any money or time on this system due to poor performance.

Current technology can support as much as 120g ram

it's possible that when the motherboard was made 2gb memory sticks were either not available or prohibitively expensive buy a 2 GB stick on ebay of the right type of memory and try it

Thanks for the answers. I have other computers, I just want to get this one performing as well as possible. Thanks again!

The 2GB limit is probably due to the hardware in that machine, it cannot address more than that....

The 2GB limit is a feature of that old motherboard.

You should purchase a new computer.