You're clearly having trouble either selecting appropriate software for your computing hardware, or managing said software. This has nothing to do with the hardware being inadequate.
I like to think that I install the software, bare bones style, I only implement approved updates, and try not to overload the OS with BS packages that just take up space and cause congestion.
I keep TSRs down to less than 5, my AV, Video card, and Audio controller are the only thing I allow in the Task-bar. Windows, puts in the network and Volume for me.
I use Avast, and turn off active scanning when I'm working on graphics. I turn it back on when I surf. I make sure I do a full scan every month, and use SpyBot online as well.
I use everything I install, and I only install what I need to get the job done.
The biggest trouble I think is what I do. Graphics design. All the programs have to write arrays out, this is where the CPU and memory of the GPU get a real workout. Even with tri-SLI the cards have to take some time to report the render. On average about 3 seconds, on a bad day about 20 seconds.
Graphics software:
Autodesk 3DS Max 2012
Adobe CS 4 Design Suite
Corel Paintshop Pro Photo 3x
Mesh Editor 2
Orbiter is the only game/sim I have installed, I get about 25/30 FPS on a good add-on, but the tri-SLI should be able to handle a lot more.
Productivity:
MS Office 2010 Home and Student
IE 8.0
Expression Web 4
Visual Studio 2010 Pro
7Zip
Win Rar
If a future computer were to work for me it would have to handle all this and more, and report renders in less than 1 sec. It would also give Orbiter over 30 FPS without the occasional hiccup.