I was reading your other post, and with vista going from 1GB to 4GB should help.
Vista is a memory hog, but please understand that adding more RAM does not necessarily speed up your system. The amount of RAM you have is similar to the amount of HDD space you have. If you’re not using all the space on your HDD there is no need to upgrade, same holds true for RAM.
With only 1GB before, the OS was likely using more then ½ of that, leaving only a few MB for applications. Now you should have more then enough memory to host anything you plan on doing unless you go extreme (running VM’s, a local instance of SQL, etc)
To make your system faster with more memory you’ll want to buy faster RAM. All memory has a CAS latency rating, the lower the better. If you bought value RAM chances are it has a CAS rating of 5, some vendors now offer CAS4 notebook memory.
The other way to make the best out of more memory is to upgrade to an x64 OS (i.e. Vista 64). There are many memory restriction with a x86 OS (i.e. Vista 32), page pool and non-page pool memory are perfect examples, no matter how much RAM you have, an x86 OS can only use under 200MB of page pool and non-page pool memory, x64 can use more … but in reality, unless you’re doing some serious computing (much more then IE, documents, and gaming) you’re probably not even coming close to the x86 memory restrictions.