Wine is what most look upon as a Windows emulator, though the developers prefer Windows compatibility layer. And that’s for a good reason, as Wine is a lot more seamless than you would expect of an emulator. And this isn’t virtualisation, where you run a Windows “virtual machine” inside Ubuntu, in effect running two operating systems at once. Wine makes it possible to run many Windows programs as though they were “native”, meaning just like any other Linux programs in Ubuntu.
While the programs will look as they do in Windows, they’ll be themed by Ubuntu (the window borders and titlebars), including desktop effects like window wobble. Like I said, they’ll pretty much be like any other Ubuntu programs, but might take a few seconds longer to load than in Windows.
Wine sets up a fake C: drive within its own folder, but you can browse through your entire system when importing or saving files in your Windows apps. You can even configure Wine to assign drive letters to commonly-used folders in your home folder, thereby making it simple to browse to them when opening or saving files.
Wine is easily installed via Synaptic, but you will need to enable “universe” and “multiverse” repos first.
Visit WineHQ for more general info, or check out the database of Wine programs (the list of popular games that run in Ubuntu is quite impressive). For those who want the latest available beta packages, you can find detailed info on how to add the WineHQ APT Repository for different versions of Ubuntu.
And remember: if you are having problems getting a certain program to run, or run without errors, join WineHQ and submit a bug report. It can be well worth the effort, as I have had Wine updates come out two days later with the fix I needed for programs like DVD Shrink.