1 GB Ram. I have a Dell 1.8 GHz system. I do not do games but I do use a number of applications and peripherals at the same time. Do I gain anything by having 1 GB RAM? At what point does 1 GB become useful. Is it likely that some of my RAM is going unused?

Part of it really depends what kind of applications you are using. If you mean you run Word, Winamp, Excel, Solitaire, Internet Explorer, etc, then it's really not worth it. If you do run any "memory intensive" applications, which usually include, but are not limited to, video editing, sound editing, 3D modeling, heavy-duty software developement, etc. then a gig of RAM can definitely be good for you. RAM is cheap enough these days that having too much really isn't an issue. The more RAM you have (within reason) will prevent the system from using a file on the hard drive called the page file. This is "virtual memory" for Windows in case you run out of available RAM. While most users will not notice much performance degredation from a lot of "paging", if you do use any of the memory intensive type apps listed above, you most likely will notice some lag. It's all about what you use your computer for.

windows xp love a lot of ram so the more is better my brother have 1.5gb of ram in his computer and it worked flawlessly, his game improvements improved a little bit as well

512 works fine for me. never haqd it use more than 400 at any one time. 1 gig wont hert you any.