Nooooo, don't stay away from Dell, include all brands! Anyway this website gives a bit of info on the various letter suffixes that intel uses on their cpus. http://www.velocitymicro.com/blog/desktop-vs-mobile-processors-whats-difference/
Basically the HQ variants are more powerful than their U counterparts and a i7-U in desktop terms is more like an i3 lol. Basically, if you think you need or would like the better processing power then go for the HQ otherwise save and get the U. Btw HQ has nothing to do with hyperthreading technology, those technologies depend on the cpu type (i3, i5, i7) and not if it was for a laptop/desktop.