High "% disk time" when building large solution

Microsoft Visual Studio .NET

We use a fairly large solution (over 200 projects). I will spare you with the 
details why the solution contains that many projects. Loading and building 
the solution takes a very long time (almost 1 hour). I did some investigation 
and it shows that during building the "% disk time" is almost 100%.

I checked with the FileMonitor (from SysInternals) and it looks like that 
all assemblies are loaded over and over again. RAM has been upgraded to 1GB 
to make sure that a lot of data can be cached, but build times are still 

When nothing has changed and VS.NET only wants to find out if it needs to 
rebuild something it also takes a very long time. It also tries to rebuild 
projects that haven't been changed at all (even dependant projects haven't 
been changed). This costs us a lot of time (and money of course).

This anyone know how to speed up things a bit? Using a makefile would 
probably have been faster then this.
why don't you use configuration to set the projects you know haven't changed
to not compile.

i have a solution with 20-25 projects. I know only 2 change. so i have all
the others set to not compile in configuration manager. so only my 2
projects recompile.

just an idea. it works must faster.

the reason i do this is because i had the same problem. If I hit 'build
solution' it rebuilds everything even though most of the projects never
changed. some how, vs.net gets confused that certain projects really didn't
change, but compiles anyway.