Applications other than those that are built into Windows Home Server are supported, if at all, by the publisher or OEM, not by Microsoft. In general, however, if it's not available as an add-in for Windows Home Server, you should not expect it to be supported. It may work, but you're likely to be on your own as far as installation, configuration, and support.
In general, I would recommend that you not install applications that are intended to manage/work with disk configuration, networking, etc. (Anything that WHS might need for it's own operation, in other words.) If you have storage needs that are likely to be greater than a couple of GB, you should add a disk which you won't place in the storage pool for that use.
And you should keep in mind that a major cause of system instability on any computer is constant installation, uninstallation, and upgrading of software. Windows Home Server is not a desktop operating system, and in general servers perform best when they're not used as multipurpose devices. So you should choose what you add to your server carefully.
I'm not on the WHS team, I just post a lot. :)
