To add to this already great post by the OP.
The biggest thing you can do to make this game better not only for yourself but for everyone is wash/repeat any bug you find.
What I mean is this
Bug Happens = Try and repeat it. Use in game video or whatever resources you have to capture the bug if possible.
Always list off your Computer Specs and Information along with driver versions (this makes a big difference even for 2 rigs that are the exact same in hardware but running different drivers)
Make sure to list off your monitor along with res and Hertz that your monitor is running at. I say this because there are many people in this game that play on various equipment. Monitors now days along with older monitors can range from anywhere to 50hz to over 200hz (if you have a wad of cash to blow on it)
Attach a crash report if possible.
What Arena/Map you where in and was it Full or light in players. (This is a server load issue, ensure you let them know when your seeing these problems, was server full or empty)
Can you repeat your problem in offline mode? (This is a connectivity test, if you are seeing studders in Online and Offline, then it is not your connection or theirs) This can help you narrow down a problem in your video card, sound card, or memory. Yes Sound devices can cause effects to become visual as the computer tried to sync Audio and Video together.
As an IT tech I will tell you now, I have serious doubts that I could not get any single one of your PC's running this game playably with just a little work and research. But I am not at your computer. You are, do some reading and digging and I am more than certain that you can find that answers to many of the problems you guys are having.
If you PC is just not strong enough to run the game. I would suggest you check out Pricewatch.com. You can find some very very cheap upgrades to what your already using that will fit just about any computer out there and can fit just about anyones budget. Seriously you pay 15$ a month to play a game, willing to bet many of you also have Cable TV and other things that you spend much more money in then your computer. So what is $30 really going to hurt you in the overall scheme of things. It would allow you to play this game that you obviously care so much about.
Lastly, requesting that a product stay in an era of visual quality that was surpassed 10years ago is rather selfish and not look at the big picture. What does not get better and improved, normally gets thrown to the wayside. Even toilet paper gets improved on a yearly basis. I can play this game on a system I built 6 years ago simply as a storage device for my online needed files for IT. I am pretty sure with just a little adjustments your PC will work just fine.