Windows 7 is installed on my C drive, which is quite small. I am very tired of instructing new programs to put their files on my larger D drive during installation; I would like to change the default drive.

This article says that you can use a registry hack, but I am giving Microsoft the benefit of the doubt and naively assuming that a configuration option exists somewhere. It's 2010... do I really have to hack my registry to make a simple tweak like this?

Also, there's a ServerFault question that explains how to move the "Users" directory and create a symlink, which could also work. However, at the moment I have some apps in C:\Program Files, some apps in C:\Program Files (x86), and some apps in the corresponding folders on D:\, so it would be a hassle.

Also, my small OS boot drive is a 10k RPM WD Raptor, and I feel like that probably gives a speed boost to apps installed on it that need to read & write to their directories a bunch. I wonder if it actually matters.