You can quickly send an e-mail that will show your calendar availability. This can make it much easier to set up an appointment with another person.
You can create a rule that will drop a copy of an e-mail into a specific folder. This will allow you to keep track of the items you can not take action on until you receive a response. This will work the same in Outlook 2003 and Outlook 2007.
Changing a few simple settings within your Windows 7 Search window will make it easier for you to find important documents and e-mails.
Using the keyboard to navigate folders and files will save you time. It's much faster then visually searching for a folder and using your mouse.
Run Disk Cleanup & Disk Defragmenter at least once/month.
Disk Cleanup: Frees up disk space
Disk Defragmenter: Organizes files for optimum speed