TFS has a reputation of being difficult to install. Even those of us setting up TFS on a regular basis know that it requires a good deal of discipline to avoid having to start over again.
Good news is that this is going to change in TFS 2010! TFS 2010 now has a two-phase setup process. When you put in the installation media (both 32- and 64-bit Windows supported for 2010 by the way!) and start the installer the following screen allows you to select the bits to install:

Installation in this case means copy to the local hard-drive. After the installation has completed you can go to the configuration phase where the actual setup of TFS components happen.

The configuration offers easy setup of a default configuration (much, much simpler than the 2008 installation!) as well as a custom configuratio where we can choose location things such as WSS or reporting services. In 2010 it’s not even required to use these services! There’s also an upgrade wizard if you’re upgrading from TFS 2008 (more on that in a later post).
Note: there is an incompatibility in beta1 between .NET framwork version that may case the configuration of Sharepoint to fail unless the following instruction is followed: TFS 2010 Beta 1: Don’t run initial configuration from the administration console (MMC)
Another great improvement in the setup is that prerequisites and configuration entries are validated before the configuration is finalized. This gives you information up front of things that needs to be corrected and normally would make the installation of TFS fail.
I've done a couple of installations by now and it's generally been a breeze. If you want a quick walk-through on the process, take a look at this 10-4 episode where Brian Keller installs and configures TFS 2010 in a virtual environment.
And as always - go through the readme file and setup guide. There are some valuable tips in there that will save you from trouble-shooting for hours later...