Wine does not require Microsoft Windows, as it is a completely free alternative implementation of the Windows API consisting of 100% non-Microsoft code, however Wine can optionally use native Windows DLLs if they are available. Wine is a program loader, allowing many unmodified Windows programs to run on x86-based Unix.
Utilities for Wine
Wine-doors is an application designed to make installing Windows software into Wine much easier. It is essentially a package management tool for Windows software on Linux systems, like Synaptic for Ubuntu.
winetricks is a script to download and install various redistributable runtime libraries into your Wine setup to be able to run certain applications.
Tips & Tricks
By default, Wine uses Windows colour scheme for the applications GUIs.
But this doesn't fit very well with Ubuntus colours.
Wine-doors already gives you the possibility to install a set of colors that fit well with Ubuntus desktop look, but In the Ubuntu forums, there's a good guide about how to change the colour scheme by hand.