Hi there, Vista requires more ram than 512MB if is Home Premium / Business / Ultimate, unless you strip vista from all other services and themes. The reason you are running slow is because you are using pass 512MB and the rest is being used as HDD virtual memory. Which is way too slow for your system, so my recommendation is to run Vista with a minimum of 2gigs. That should help you and you can try running it with 1gig but if you end up using heavy load software's you will notice the same issue again. Also the speed of your RAM and CPU processor will matter.

Windows Vista Basic
*1 GHz 32-bit (x86) or 64-bit (x64) processor
*512 MB of system memory
*20 GB hard drive with at least 15 GB of available space
*Support for DirectX 9 graphics and 32 MB of graphics memory
*DVD-ROM drive
*Audio Output
*Internet access (fees may apply)

Good enough for web surfing but not good enough to run most applications. Unless you upgrade the memory to 1gig and CPU to 1.4-8Ghz in my opinion. Other version of vista such as "Home Premium / Business / Ultimate" will require a minimum of 1gig of ram I still advice 2gig to 4gig max if your system can support it. Also make sure you have the correct video drivers installed as well. That will smooth things a bit too I have notice with vista.

Usually, Windows instantly picks up possible problems with your pc's storage and features a notice that demands if you want to run the Memory Diagnostics Software.

At least serious of these problems are actually caused no memory of itself, but by the user of the application in run time. The sad fact is that some applications just not well written, there is a tendency to cover the area outside the program itself is running. Memory location