Folks, just for your information, cases such as the iBall baby 207 are not HTPC cases. These are ordinary computer cabinets. The basic idea of an HTPC cabinet is the shape - like an AVR. Modern HTPC cases also come with small monitors for use. In most cases, you mount the HTPC on a equipment rack and use your main TV or projector for use. Ideally, an HTPC is used only to store music and movies and does not have any programs that is not related to A/V.
Ideally, the HTPC machine should not be used for regular computer usage such as surfing, word processing, chat, etc. You should have laptop or a different machine for that.
One of the main reasons for keeping the HTPC machine clean is to give it the freedom to play movies and music well. I have seen players skipping or pausing frames in a movie when the CPU time is hogged by an external program. Similarly when you are playing a song, the system could pause for a second or so. or even skip part of a track.
I would also recommend that you look at 4 to 8 GB of RAM for uninterrupted use.