A couple months ago I bought my first Mac computer with the release of the new MacBook Pros. The new machine is beautiful and the switch to OS X from Windows has been primarily positive overall.
There were a few things from Windows that I greatly missed, but I found solutions which worked:
Make Safari open new windows in new tabs (especially links in Gmail messages), just like Firefox: http://hetima.com/safari/stand-e.html
My Bluetooth Mouse was extremely difficult to use with the OS X mouse acceleration settings. Fortunately after trying several options I found a program that fixed the problem for me: http://www.usboverdrive.com/
Create “new document” context menu option in Finder to create a quick way to make a new Word document or Text document in a specific folder: http://www.growlichat.com/NuFile.php
Combine multiple buddy lists into one in iChat: http://www.ksuther.com/chax/
Quickly lock your computer like Windows Key + L: http://www.gkoya.com/2006/11/23/locktight-for-mac-os-x-intel/