The not finding the mpq data dll thingy is probably because you downloaded the wrong installer. Download the one that matches your system architecture and try again.
When in doubt: Accuse the user that it was his own fault!
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."
~ Rich Cook
Still feels too slow. It took forever (2-3 minutes) to load up, and after that, the UI felt a little unresponsive.
Also, is there any reason it needs to be allocating 128mb of my RAM? Seems a little unnecessary, honestly (especially when you look at something like VC++ Express, which is currently using 17-20mb, under the 'same' conditions [start page, nothing open]).
Edit: Eww, mercurial.
Debug mode would also be a reason why it's allocating more memory than needed.