Windows 7 Forums have a new article featuring 19 ways to speed up Windows 7. Here's a taster:

1. Boost your RAM - Windows 7 is very efficient at using your memory and adding another stick of RAM can give a big performance boost at very little cost. 4GB is plenty for most 64-bit users, and 3GB is a sensible limit for 32-bit users (mainly due to the memory limitations which you can read about here). If you do more intensive work such as CAD or video editing then added even more than 4GB RAM may be a sensible idea. However it should be noted that simply adding lots of extra memory will not continue to improve overall performance, the bottleneck depends on other components (such as your CPU and hard drive).

2. Switch to SSD - Using a Solid State Drive is going to provide a performance boost in almost all Windows 7 applications, especially when it comes to boot times. SSD's have no moving parts and therefore are silent and more energy efficient, with the benefit of much faster access times. The current generation of mechanical hard drives will be obsolete in the coming years, but for the time being SSDs are quite expensive. If you have the money and a high end system to improve upon, this would be an excellent choice.

3. Install the Correct Version of Windows 7 - If you have a high end PC with over 3GB of ram then you should be using the 64-bit version of Windows in most cases. Limitations of 32-bit hardware/software will prevent the use of all the memory a little past the 3GB mark, so you could be wasting the potential of your RAM. There are many other reasons to choose between 32-bit and 64-bit Windows 7, which are covered in more detail in this article. If you have 64-bit hardware then you may as well make the most of it.