Memory Upgrade Problems PLEASE HELP

I have a gateway MX230 notebook with a intel 1.5 Ghz celeron proccesor, 256 mb ram and a Via/S3 video thing. I have bought memory many times and none of them seem to work. I called up gateway and asked for specific requirments on memory for my laptop. They where
1.DDR 2
2.PC 4200
3. Pin count 200

I bought a 1 gig stick today a circuit city that met alll the requirments(it had Pc 25300) but the sales guy said it would not matter. I really need this upgrade or I will end up having to buy a new laptop wich is someting i do not want to do. Is there anything i need to download or install? Please HELP!!!!

 

http://support.gateway.com/support/memory/memory.asp

Try this,maybe you will find the right memory.

 

I did some Googling and couldn't find your model number. Are you sure you didn't mistype? Also, visit http://www.crucial.com. You can use the memory advisor tool to look up your model or if you are using the computer, the website will scan the computer and tell you what kind of memory you need. Hope this helps.

 

yeh that was a typo, its a gateway MX3230

 

http://support.gateway.com/s/Mobile/Q106/MagicLC/1009037sp2.shtml

I don't think that buying 1gb as single stick is wise,cos your mobo support only 1gb.Maybe 2x512 mb will do the job.
And please use this link to find right memory:http://support.gateway.com/support/memory/memory.asp