If you recently purchased a new Acer Aspire Revo or a similar low powered HTPC, you might have noticed that there is a bunch of software installed on the machine that is not necessary. Please please please do not leave this stuff installed on the computer. Take an hour or 2 or 3 and sit down and uninstall basically everything that is on the machine. All of these little applications are most likely dragging down your Revo and making it not perform how you would like. Anything that is running down in the system tray really needs to be un-installed, especially if it is some kind of anit-virus software. I still recommend anti-virus software, but download and install Microsoft Security Essentials, which is free! I have this installed, with real time scanning OFF, but do have it scan every night for viruses. Since this is a HTPC your chances of viruses are very very low.
I also recommend get all of the latest drivers from nvidia.com, and don't forget to install all of the windows updates. Still not happy? Perhaps try reformatting the machine and put a clean version of Windows 7 on it, this will ensure there is no bloatware dragging it down. Don't forget to ensure all of your BIOS settings are correct.
I hope these tips help!