Operating System Not Using All Of RAM

So, I have been recording game-play, using FRAPS... Which creates incredibly massive files (Over 80GB for about an hour). This is because it doesn't encode or compress it.
I am now putting it through Windows Movie Maker (a quick and easy way) to compress it. A 5 Gig file went to less than 250 Megs.
My question here is while I was making sure it was using all of the CPU (not sure how to correctly say that, is it a verb or a noun? :O) space. While I was doing this I saw that the Physically Memory was at 50% and the sum of the processes didn't come close to 8 Gigs. Wow. I forgot to check the process from all users. Disregarding that and going on with my current theory; Is it possible that my computer is not fully using the 8 Gigs of RAM I have? (Yes, 64-Bit Windows.) Also, my fan has not worked since I can remember. I have re-installed Windows quite a few times (on the same computer so I hope that's still legal. :O) and the network drivers don't even appear on the search for drivers. I am wondering if my fan driver isn't there and hence why my computer is so slow sometimes.

Never heard of such a thing as a fan driver. Fans generally don't work because they have failed or have become disconnected.

Regarding RAM, I'd assume Windows and your apps are using what they need to use. I have 4 GB of RAM. Right now, I'm using less than 2 GB of it. If Windows thought assigning more RAM would be useful to do what I'm doing right now, I reckon Windows would assign more to the tasks.

Hmm... I am assuming as well that Windows Movie Maker is not using all it can because it's a 32-bit program.
A 32-bit program can still work on 64-bit but can it take advantage of the memory?

It's been about six hours... And Windows Movie Maker is 94% complete... Please don't crash... :P
It's taking on over 150GB of data though... Not sure if that's a good speed or not.

Also, why are there so many guests looking at this post at the moment? Are they just bots that serve one or more of many different reasons? I don't think many other people would be doing this at this time. :P But I could be wrong. This -is- the official forum... Right? :P

Also, why are there so many guests looking at this post at the moment? Are they just bots that serve one or more of many different reasons? I don't think many other people would be doing this at this time. :P But I could be wrong. This -is- the official forum... Right? :P

Guests are non members who are currently accessing the page in question. Typically guests will outnumber members by a wide margin. That is the way things are on a public forum.

A 32 bit process can normally access a maximum of 2 GB RAM and even that would be highly unusual. Adding up the memory usage items in the process list rarely provides meaningful information. The default columns shown by Task Manager don't show full memory usage and there are some very significant users of memory that are not processes. Windows memory manager always maintains control over process memory usage, always with the goal of maximizing overall system performance. This is far more complex than you imagine.