One of my recent annoyances comes from IT support providing a developer, like me, with a laptop pre-installed with all the corporate mumbo jumbo. And in my case they do the installation using ghost images or ghost installations, so the OS is not really configured for the hardware of your particular machine, which in some cases results in messages appearing on-screen relating to graphics drivers crashing. Thats my opinion anyway. IT support also generally also install whatever anti-virus whether its any good or not, which in most cases slows the machine down. I have also had software installed on my machine that affects localhost on IIS for some reason, which I cannot use for development when I am connected to the network, but when I disconnect I can. I have no idea which piece of software is causing this, and I can think of one particular piece of software that could be causing this. Personally I would prefer installing Windows 7 from the start at some point, with the appropriate and correct device drivers.
In my opinion devs should be allowed to take total ownership of their dev machine which includes OS maintenance and installation. In this way they are totally accountable for any problems that may occur and you will find that most devs need to know what the OS can do and what not, so its best for them to take ownership. My current machine has 8GB of RAM and has a core i7 processor but it does not feel that quick in some cases, but maybe thats just me.