Maya 8.5 file lags during playback

If anyone in this forum knows anything about Maya, this question's for you:

I recently bought a new 64-bit HP to aid me in handling a current project that is a very large .ma file (74 MB). The file uses Anzovin Setup Machine and Face Machine, and I was told that all I would need in order to use the file is the Anzovin Rig Nodes for 64-bit, which I downloaded from the site. The file loads fine in Maya 8.5 (Service Pack 1 for 64 bit), but when I scrub the timeline or even hit the play button, there is an incredible lag that makes it impossible to get timing right when trying to animate. I have until Friday to take this computer back and I'd rather not because this is pretty much the only problem I've noticed with it.

I set my paging file to the maximum of 10747 MB after reading a forum about paging files, but the problem is still there.

This is the same problem I had on my last computer, which was 4 years old. I'd expect this new computer to do much better. Is there something I'm missing? Here are my specs:

HP Pavilion m9402f
Windows Vista Home Premium x64
AMD Phenom(tm) Quad-Core Processor 2.30 GHz
7.00 GB RAM

Please help!!! Thanks in advance!

Could it be your graphics card? Perhaps it isn't powerful enough considering that you are running such a resource intensive software.

Another thing, could it be the .ma file which contains too many polygons or something to makes it lag?

It shouldn't be the graphics card. I bought the NVIDIA GeForce 9800GT in addition to the computer, and that was the most powerful one Best Buy had at the time (which was only 2 weeks ago). I had to buy a faster power supply just so the computer could handle it.

As far as the .ma file, it definitely has a lot of polygons. It's 74 MB, and unfortunately the rigged characters don't come with an unsmoothed option. There is an extensive environment that they're in as well, and I've turned off and even deleted a lot of it just so I could concentrate on the animation and not the environment, but I still left a couple of things on that I could probably do without. I'll try that and see if it helps.

Is there anything else that you could think of?

Nothing that I know of. I never used maya before, why not you try contacting autodesk and ask them about this.

Have you updated your graphics card drivers?