hi justin,
we'll need a little more information. Memory can be confusing 'cause it often gets refer to as more than one thing. It's geneally refered to as RAM or computer memory, and is talked about in terms of MB so you might have say 64 MB of memory, 128 MB, 256 MG or maybe 512 MB. There is also hard drive size which used to be in MB but is now mostly in GB. Back in 1992 i had a 1000 MB hard drive (also called 1 GB hard drive). now hard drives are up all the way to 750 GB in size. common sizes are like 60 or 80 GB.
Memory (or RAM) is not where your programs or data files are kept. memory is temporary and doesn't "save" anything.
Hard drive is where your files and programs are installed. This is "premanent" storage (at least until your hard drive breaks).
you can double left click on your "my computer" icon and then on your Drive C icon right click and select properties. this will pop up a little graph of your hard drive telling you how big it is and how much space you've used vs how much is left on the drive. let us know what that says.
you also from your desktop, you'll need to right click on your "my computer" icon and select properties and that will pop up a box that should tell you some information about your computer, like what version of windows you have, what the speed of your processor is, and how much memory you have. let us know how much memory it says you have (which it might only refer to as RAM and not memory).
alternatively you can go to this web page:
http://www.belarc.com/free_download.html
dowload the Belarc advisor which after you run it will give you a very detailed run down of your computer. then you could just type that information out to us, or copy and paste (i think you can copy and paste it). the program doesn't send any information to those people, it just tells you what you have. it might look like it cause it uses a web browser to report your information to you, but it's ok it's not sending any information about you.
after you do that and post again, we should be able to tell you what to do. you might need to add a second larger hard drive or add more memory. if the message you get is really about "memory" then it's not your hard drive and deleting programs or files and stuff will do NO good. Because you are removing those from your hard drive and not from memory. You might have a virus or spyware that is taking up memory.
you can go here and download Spybot S&D and install and run it to see if it catches anything:
http://www.safer-networking.org/en/mirrors/index.html
here are instructions on how to use spybot:
http://www.foxware.com/security/spybot/spybot.htm