Will my pc handle more memory?

My pc only has 128mb, the max capacity is 512mb..........can I add more than 512mb?

This will depend on your motherboard. Where did you see 512 MB as the max capacity? If your computer or motherboard manual or datasheet lists 512 MB as the maximum than chances are you can't use more than that. Occasionally there are firmware updates to allow the motherboard to use denser memory than it originally could.

Assuming your PC takes standard motherboards you may just want to replace it with a new board with a faster CPU and more RAM.

As of a "max capacity," I have heard of no such thing. Other than having a maximum of X slots on the motherboard, and at the current time 1 gigabyte per slot. As filletofspam said, if a manual or data sheet says 512 Megabytes as the maximum capacity, that's probably all it can hold. And looking at 512 Megabytes max, you REALLY need to UPGRADE! As my computer uses 512 Megabytes as soon as it boots up, and uses 1.3 Gigabytes when in a game, and I have 1.5 Gigabytes max..so that computer must definitely be very weak. I do suggest getting a new Motherboard, at least 1 Gigabyte of RAM, PC3200 DDR400 is my suggestion of what you should get. Get a Pentium 4 2400+ with hyper threading or something like a dual core. Make sure you get a board that can support it :D