For whatever reason, the forum refuses to let me respond to the thread above.... anyway:
The difference between Turbo Tax Premier and Deluxe is whether or not you need to file for a sole proprietership business or have rental property. You can get a list of the differences at Intuit's site: http://www.turbotax.com/tax_products/online_products.html?source=ttcommain&priorityCode=3025930788 but chances are you don't need Premier.
As for installing TT 2005, go into the CXOffice setup and create a new win98 bottle (or modify the one you already created for TT) and install IE 6.0 into that bottle from the setup screen. After that's done, you can install your TT software into the existing bottle (don't create a new one) and it should have no problems as long as IE is already installed in the bottle.