I've looked a little at Cosmos FloWorks - as long as your problem is relatively simple (no mixed phase stuff, no combustion stuff, etc.), then that would work pretty well. Easy to use from SolidWorks.
I've never used Cool-it, but from their web page descriptions it might be a good fit - supposedly easy to use, made for electronic cooling. However, from their webpage they use non-conformal (grid based) meshing - which can lead to alot of elements, large models, and insufficient number of elements in boundary layers (especially if you curved parts or parts angled from the grid. It has been the standard for many of the electronic packaging CFD packages (like Flotherm and IcePak) for years, and I guess people got good results from it.
You could also look at some of the more general CFD packages. May not have built in wizards for heatsinks and the such, but that is all pretty easy to model from a CAD software. CFDesign is pretty easy to use, uses a tet mesh combine with polyhedrals near parts. Also Star-CD has a easy to use package called CometWorks which might work for you. More expensive packages like Ansys CFX would work, but more than you need. Also look at IcePak (from Fluent) and FloTherm - 2 of the big guys in electronic packaging CFD. Both use the same type of mesh generation as Cool-it.
Good luck - my guess is that Cool-it might be a good way for you to go, especially if you don't have much CFD experience.