Yeah i do this aswell, except i use an air compressor to blast the dust. I'd never use a vaccume with parts like the CPU, Motherboard, hardrive,RAM,etc,etc because of the static.Well to be honest, last week when installing the new hard drives, I basically decided to take everything out of the PC and clean the parts individually.
The motherboard wasn't too bad. I just gave it a wipe down from dust.
I used a dry cloth on the rest of the components. No problems what so ever. Its just a lot cleaner.
I did use a vacuum on the PSU as I wasn't going to open it, and on the CPU cooler.