The IT support group where I (used to) work (but still keep an oar in) warns against IE8. They say that some usual internet services don't work properly with IE8.
They never approved use of VISTA on their network. They are now exercising widely-used applications on W7 prior to approving its use. Until such approval, they install XP on all new machines purchased through the central ordering system. They claim that they will convert these machines to W7 once they approve of its use. I wonder whether they know of some magic way of doing the XP->W7 migration.