I Have a 2 x 256mb new Ram cards i want to install into my computer, which is a gateway machine from 1998. My problem is when i try to install the ram into the machine, the ram slots have a extra bump in them which makes it impossible for me to install the new cards - how can i work around this?

You can't. That is called a key and is designed to prevent you from installing the wrong RAM in the improper slot.
Which one does it look like?

SDram

DDR RAM

RDRAM

Do not worry if they do not look exactly like yours. Make sure the notches along the edge with the gold pins are the same as yours, and let us know which one you have.
Please list the specifications about yor computer so that we can advise you accurately.

the ram looks exactly like the ddr ram, with one hole in the middle. i cant install this ram because the ram slots and the old ram look like the SDram - is there way around this?

Sorry to say you have the wrong RAM. You will have to buy SDram to make it work. Do you know what proccessor you have and the speed? Is it PC100 or PC133?

on the motherboard it says "PC133", so i guess i do have the wrong ram. But we are getting a new computer soon, so would i be able to just plug the new ram i got now straight into the motherboard and let windows ajust, or will i have to reinstall windows?

Yes. 128mb PC133 RAM on eBay is only $10 to $15 dollars. How many slots do you have?

There are many types of RAM. Your new computer may not be compatible with the RAM you already have. For instance, new Dells often have all their RAM slots already filled and no room for more. And the RAM has to be the same type or a speed that your computer can handle. First you get the computer, then you find RAM for it. That's the easy way.

New computers will come with DDR or DDR2 Ram, and then the type must still be supported by the motherboard.

PC2100, PC3200, etc.