So, if I buy an Ipad App......can I also use it on my Ipod Touch, or do I need to buy the Touch version of the same App if I want it?

I see all of my Touch Apps showed up on my Pad, some of which I will delete off of it bacause of the size. I guess my question is.....if I buy an HD App.....do I also get the Touch version with it? That would be nice!!!!

The "HD" version will not download to your iPod Touch. There are, however, some apps that recognize the device they are loaded on so that you do not need duplicate versions of the same app, i.e. iBooks, Kindle, Pandora, Stanza and my all time favorite (so far!), the Atomic browser (to name a few of the ones I have.)

If you look at your apps in iTunes, you will see that they are broken down into three categories:
1) iPhone, iPod Touch and iPad apps. These will work on any device with the appropriate screen resolution.
2) iPhone and iPod Touch apps. These will work on the iPad, but the screen size will be the same as on the iPhone/iPod Touch. (But you can use the 2X button to fill the screen)
3) iPad apps. These will only work on the iPad.