I'm still running an XP, DirectX 9.0c. Questions:

1.) What is the purpose of DirectX?

2.) Will XP still get later versions of DirectX?

3.) What is the difference between DirectX 9 and 10 (or 11)?

4.) Will higher versions of DirectX make my games run better?

5.) Is it worth buying Windows 7 if my only concern is to run games better?

6.) I must be an idiot for asking these questions, but should I be ashamed of myself?

1) It is a tool used by developers to display 3D graphics

2) no, you must move to Windows 7 to get 10 or higher

3) I don't have a clue (haven't kept up with it). You need newer hardware to use 10/11. Since you have so many questions you probably wouldn't even notice the difference.

4) no, if they run crappy on 9, they'll run crappy on 10/11

5) no, XP should be fine. Depending on your PC you might be able to upgrade a few components

6) no, the average user shouldn't have to know all the technical details. It is one of the reasons why home consoles are so great.

EDIT: I assumed the game you were running is really a DirectX9 game, not a DirectX 10/11 game. If a game is DirectX10 compatible and you have DirectX10 compatible hardware, then it would might make sense to upgrade windows, but this really depends on the game and what it uses in DX10.

http://www.winmatrix.com/forums/index.php?/topic/9550-directx-9-0-vs-directx-10/

but this forum makes it seem like the difference is so huge...... i don't get it. is it fake?

1. DirectX or Direct 3D is an API that renders 3D Graphics.
2. No, Direct X 10 requires Vista and above and Direct X 11 requires Windows 7.
3. Both require faster graphics cards and produce better graphics.
4. Not really, higher versions of Direct X are more hardware demanding.
5. games are often less hardware demanding on XP. But if you have a Direct X 10/11 capable GPU and more than 2gb of RAM then you should upgrade.
6. No, feel free to ask for help anytime.

no, it isn't fake. There is a difference, but only for games that actually use DirectX 10 (Microsoft Flight Simulator will run on 9 or 10). I honestly don't know which features are new in 10/11, but 10/11 are better. They just won't magically make a DirectX9 game look/run better. You need better hardware to run the better software. Also, I wouldn't be surprised if there is something else going on in the background for those screens to make DirectX 10 look so much better.

I will point out that many games that are worth playing on the PC nowadays have options to run DX10 effects. In fact Metro 2033 has an option for running DX11 effects. They run on DX9 as well, but they have all the shiny DX10 effects as well.

1. Already covered.

2. No, however you can find groups that hack the registry and installation to run DX10 on XP. The downfall is that since it's not official this can screw up your DX during install. IF you MUST run DX10/11 you are better off installing Windows 7.

3. You won'y find DX Shaders in DX5. DX10/11 is I believe are using Shaders 2 or 3. I also believe in some cases some there has been some design improvements to speed up and simplfy development.

4. The original promise of DX improvements from a single source was that if any code improvements were made all games even old ones could benefit. There really hasn't been any performance since DX1-6 days where a lot of the backend was overhauled.

5. Honestly no. Unless you are required to play a game in DX10/11. Then I would suggest passing.

6. No, but you could probably find the answers somehwere on the net. 

MS ran a smear campaign against DX9 in hopes to lure people to buy Vista. The developers were "requested" to offer modified images of there games with features disabled. This isn't to say that some of the tools in DX10/11 aren't easier to use, but for the most part DX9 can perform the same stuff, just with some more work.

There are negligible differences: http://www.computerandvideogames.com/article.php?id=176533 . DX10 was overhyped by Microsoft with the intent of bringing gamers to Windows Vista. The same goes for DX11 and Windows 7.
BTW Xbox360 uses directx 9.0c.

There is not much difference, with games today and for the foreseeable future. DX10 and 11 bring small eye candy upgrades to those who have the hardware and Vista or above, but nothing worth upgrading to unless you're already buying the new card for its processing power.

In the future, DX11 (and OpenCL) may be important for GPU compute, but that's a niche market right now.

Basically - are you happy with your current graphics performance? If so, stick with your current setup.