That's odd. The version shouldn't matter, the difference between strawberry and Active State could. It will be Monday before I can run your code on my Win XP machine and see what it looks like. The version of Windows may matter?

Update: I was finally able to run the code to see the issue. The MS button has slightly beveled corners whereas the Tk button has straight edges. The human eyeball picks up on this right away. although the difference is actually quite slight. The font style, spacing, border can all be dealt with and I see some code for that below. The result is "very close", but not exactly like the MS button. I don't know of any way to make a generic TK button with "rounded corners".

You can get a consistent look to your GUI. I've never had a complaint about "looks bad". I get complaints about "hey, I wanted to do X and I couldn't figure out to do it!". Great GUI design is hard to do, but if you succeed in making something non-trivial that is genuinely easy to use, nobody will care about squared edges.