What is the driver version? If it is not 178.24, go here
http://www.nvidia.com/object/winxp_178.24_whql.html and download it.
When your system says it has 256mb video memory, that is really a false assumption. What you are seeing is what is supported. The video card "borrows" system memory. System memory is much slower bus speed, and Windows decides how much it can use of that 256mb at a time. The newer version of Hoster requires more horsepower to run the 3 different displays on both monitors. That is why I suggested going to Black Viper's website. If you are having problems, this can be one way to get the resources freed up to help get your system over the hump. The other is to make sure you disable all other programs that may be running in memory. Anti-virus, disk utilities, spyware, other DJ programs etc. The problem you are describing seems to be centered around video memory. The only way Windows will give more memory to the video card is if it doesn't need it elsewhere. (ie: sevices and other running programs)