using the full source version always seems to take a beating in visual studio and the DNN framework in debug.

In a 'usual' developemnt environment you will usuall have the following apps running:

• Visual Studio in 'debug mode'
• SQL server 2005 Developer
• Internet explorer / firefox
• .Net framework

If you are using the PC all day, I would reccomend a minimum of a 3GB processor with 2GB of RAM or a dual core. Microsoft did release a patch for large VB.Net application with many projects (as per DNN's framework) to speed up visual studio, but the difference is not very noticable. http://support.microsoft.com/kb/920805

Microsoft's minimum requirements are redicuasly low for visual studio and SQL server and nobody in their right mind would use a 450mhz PC for large development projects. (it's all sales talk)

As you said, a slow PC will do the job but do you have all day to watch the screen while you could be working?

I use the full source version as I have modified many parts of the DotNetNuke core.  The downside is that upgrades are a bitch - but the plus side is that I'm able to make some changes that I could not otherwise make - without waiting on the core team.

I develop on a Dell Laditude D810 2.2GHz with 2GB of ram; I ussually have two separate VS solutions open, and run SQL2K5 Dev on my workstation; my workstation runs Win2003, and I really push it's limits. (i have outlook open all the time, and I have over 80,000 items in my inbox, and 12,000 in my outbox - no joke.)

I've found these specs to be quite tolerable; ram is the most important thing.  Remember that you don't need to build every project each time you debug the app - only those that have changed.  I can ussually build and debug in 20-30 seconds; however a rebuild solution takes around 5 minutes...  but I only have to do that when I have references go out of whack for some reason.