Question regarding hypermemory

[infrd]

I noticed that Windows is eating up about 500MB of my physical memory, right after boot up. That leaves me with half my total RAM available. The question I have is, is the 256MB shared memory factored into the available memory or not? If a further 25MB is to be deducted from what I have left, I'll be left wiht a headroom of less than 200MB of RAM during everyday usage (web browsing and a few other things).