Any Disadvantage Using DVI-HDMI Adapters?

I don't think so - quality is not compromised - after all it is all digital. Provided the source is outputting data that the TV can decode. I use DVI-D (digital) to HDMI from my Mac to my HD TV - this way I can select tracks to play from the listening position by using a wireless keyboard. Note that when (if) they start protecting video against piracy then some devices will not accept digital HD signals except through HDMI...

( I had to hack the Mac standard operating system by programming the Video card to output 720p, as this was not a native resolution on Mac OS but it all works seamlessly now)

As I don't know your setup I can only relate my experience with adaptors and such. In my case dvi and component are the same. Mt tv,a 3year old Mits /without hdmi--but has dvi. ----I would guess because my tv is only 1080i is the reason. (?) Just to complicate things I guess it might also be the quality of the component cables I use. For a 1080p set I would say hdmi should be the way to go.

Thanks for all responses. My 720p projector only has DVI, no HDMI. Guess I just have to try out and see if DVI-HDMI would yield better picture quality compared to the component cables that I'm currently using.

On another note, is there a difference between a cheap HDMI/DVI cable(probably <$10) and a branded cable like the Verastarr costing more than $200?

I use monosource.com for my cables, they are priced well and they have hdmi switchboxes, dvi-hdmi cables, etc. You may want to confirm that your dvi port is hdcp compliant (can you connect a cable box to it?) to receive hd content on it.