Computer runs slow... choppy

I assembled my computer about 2 years ago, and I've never seemed to be able to get it running at optimum effiency. I was wondering if someone had any tips, or pointers or any info to help me. Or if they could even send me in the right direction. My PC is only a P3 933MHz, so I realize that it has its limits, but it's ridiculously slow at times. My girlfriend has a P3 933MHz, and it's faster than mine. I was over at my brother's house the other day, and he has a Celeron 1.2GHz that is WAY faster than mine, and I even have a better graphics card. Anyway, here are some specs:

- MSI motherboard with 133MHz/1 AGP/5 PCI slots/4 memory slots/AC '97 onboard audio/ (no onboard graphics)
- Pentium 3 933MHz processor
- NVIDIA GeForce2 MX/MX400 64 MB graphics accelerator
- 512 Megs of DDRAM
- Ethernet 10/100
- 56k dinosaur of a modem
- Windows XP pro OS

No cooling problems. Everything runs fine with no errors, but when I play any games they sputter or get choppy at times, and it seems to run like crap. An example is when my brother and I linked up our computers for a head to head battle of 'Empire Earth', his Celeron (with a GeForce MX card) was getting 35 FPS with all graphics settings at their highest. My computer was getting only 12 FPS with everything set to minimal!!! I read something about motherboard voltage settings somewhere... could that be the problem?

All my video drivers are up-to-date. I have endlessly tweaked and messed with the graphics card settings, and the BIOS settings. No luck. Anyone have any ideas or suggestions before I put my foot through my monitor?

I can get detailed info about my motherboard or BIOS if needed. Thanks for any help.

Run ad-aware/spybot S&D/CWShredder and defragment your hard drive. You could have a lot of junk slowing things down.

run "msconfig" and first take your bootlog.txt, you can read it.

And try other diagnostic bootoptions and feel the speed.

Use Task Manager to detect the process, write down them, and compare it with your brothers.

Use "msconfig" again to stop unnecessary programmes.

Use "Highjackthis" to detect Spyware Process.

I run 'hijackthis' and 'cwshredder' on a daily basis. I run spybot and adaware pretty regularly, and have no problems. I will try defragging my hard drive, but I recently installed a new 80GB drive. Within the last 2 months. I have a feeling my problems go deeper than this. Thanks for the help and suggestions, I'll let you know what happens.

I think you're right about the settings on the motherboard but I think it's more than the voltage settings. Get a detailed picture of your motherboard with the proper jumper settings. Sometimes' the manufacturer will have a tech line you can call. Have you checked the heat issue? If your computer isn't being cooled properly it will cause it to get slow and frequently to freeze or shut down. Pentium chip's are known for this. Celeron's run at a much cooler temperature therefor can handle a bit more high intensity for long periods of time without needing an extreme cooling system. StarTech makes some really great system fans. If it's your video card that isn't getting enough cooling then the system fan will help with that as well.
Good luck

hold down and press the keys ctrl-shift-esc, then tell me how many processes you have running in the task manager