The problem is they were not throughtfully checked on compilance with IE, as xing (the creator of most themes) just don't use this browser.

So you just have to check on the minor problems you might encounter and fix them. It's not a big deal, as you are going to change the preset theme anyway, or will create your own, don't you?

bughunt

First of all please mind the presense of IE7 javascript. It's a script by Dean Edwards, that re-writes the CSS styles so IE understands them correctly by adding necessary hacks "on the fly". Please read more http://dean.edwards.name/IE7/
IMHO it's an overkill. It significantly slows the redering of the page in IE. And in some cases it leads to some unexpectable glitches. So when you complain that the theme is not displayed correctly in IE, it might be the secondary effect of the script, not the theme itself. Of course, it also makes troubleshooting much more difficult.
So first you want to consider if you really need this script in your particular theme.

Go themes/templates/header_inc.tpl and turn it off by deleting the appropriate lines. If you use transparent .png images and top suckerfish menu, add necessary (necessary for IE) js fixes to the template. This fixes are in util/javascript/fixes or you can use the poison of your choise. Or, better, just don't use transparent png. Do you really need that fancy alpha channel?
Browse your site in IE to see if the layout is broken.

First of all inspect top suckerfish menu, as it's the most prone to be broken due to massive styling (read more about the suckerfish menu at http://www.alistapart.com/articles/hybrid/). If it's hard to pin down, what is cousing the problem (and it usually is), swap themes until you find the one that have it OK. there have to be some. compare the CSS styles in both, apply fixes.

If you stumble in some positional bugs you don't know what to do with — go to www.css-discuss.org and www.positioniseverything.net
If you fail — go back and turn the IE7 js on. remember it's modular, so you might turn on only the necessary parts. I personally use only selectors module (as a temporary solution).

PNG repeating backgrounds and IE7

Because of the how the PNG transparancy problem is handled in IE7, PNG's "fixed" by the script won't tile. Normally in IE7, this is handled by the fix being only applied to files ending with "-trans". In Bitweaver this is per default over ridden, so the fix is applied to all PNG's. So if you want to use repeating PNG backgrounds in combination with IE7, you'll have to find the following code in themes/templates/header_inc.tpl;

and either change it or remove it.

share your findings with the community!

We would appreciate you to submit the appropriate fixes to the bw themes. Visit irc channel, write at forums or add to this page.