I'd go with the equivalent model without the built-in tuner. The price difference is usually enough to pay for a good satellite and ota capable HD stb setup which will offer more channels and greater flexibility.
The built in tuner is usually ota-only, won't tune satellite or cable HD. A few of the newest models will tune cable HD using the QAM system, but not scrambled channels.
If your local cable system is carrying HD, the additional cost is usually only an extra $5 a month for the HD cable box and you won't need an HD tuner in the set.
The difference in price between the 2 models is only $50 for the one with the built in box. The built in tuner will accept unscrambled cable HD feeds. Around here HD is part of a $15 per month package plus another $5 per month for the HD-Digital box.
A $50 price difference makes this another matter altogether. If it works with your cable system you're good to go, if not you're not out much money and there's always the option of putting up an antenna and getting free local HD.
With the predominance of cable tv in all but the most remote areas reception over an antenna has become something of a lost art. The fact is that if you're within 50 miles or so of the broadcast towers a good antenna will produce a much better analog signal than any cable system and great HD if there are few if any obstructions between the antenna and the towers.
If you want HBO, Showtime, ESPN, Discovery HD, or any of the rapidly growing number of other non-ota HD channels you'll still have to pop for either a satellite or cable setup.