After reading the helpful reviews, i did alot of research before buying any cables to hook up my macbook to an HP HDTV. Hopefully the following will help others with connection issues:
Investigate the PC input jack of your HDTV for 3 specifications:
1) TYPE OF DVI INPUT JACK. Most newer models have DVI-I or DVI-D input jacks. there is a difference between the two. you can tell which one you have by referring to your manual. if you don't have the manual, look at the jack itself and compare to pictures (link isn't allowed here, but datapro had clear pictures)
2) DUAL or SINGLE LINK. newer model HDTVs likely have the dual link inputs. refer to your manual or look at the jack and compare to pictures.
3) MALE OR FEMALE. ihad assumed that because the apple mini-DVI to DVI cable had a FEMALE DVI connector end, then my TV must have a MALE input jack. not true. my TV has a FEMALE DVI jack. So by default, I needed an adaptor cable for the mini-DVI to DVI cable.
after this, i determined that i had a DUALLINK DVI-I FEMALE input jack. NOTE that the mini-DVI to DVI cable, not pictured online at apple.com, has a FEMALE DUAL LINK DVI-D connector end.
so I bought the apple mini-DVI to DVI cable & a DVI-D to DVI-D male/male connector cable, connected the cables to their respective hardware input jacks, and it all worked.
FYI, i got the DVI-D to DVI-D male/male connector cable instead of a DVI-D to DVI-I male/male connector cable, because i couldn't find the latter. Luckily, because my TV had a FEMALE input jack, it could take a DVI-D male (just the way the input jacks are designed).
Hope this helps.