Of course it's in HD. You get all the NBATV HD games as well as ALL the games on FoxSports.
Here is the HD lineup for NBATV.
http://www.nba.com/schedules/national_tv_schedule/NBATVHighDef/
NATIONAL TV SCHEDULE - 2004-05
Date Teams Time (ET)
Mon, Nov 8 Golden State @ Dallas
8:30 pm
Tue, Nov 9 Indiana @ Minnesota
8:00 pm
Sun, Nov 21 Cleveland @ New York
7:30 pm
Mon, Nov 22 Minnesota @ Dallas
8:30 pm
Tue, Nov 23 Toronto @ Washington
7:00 pm
Sat, Nov 27 Detroit @ Milwaukee
9:00 pm
Sun, Nov 28 New Orleans @ L.A. Lakers
9:30 pm
Mon, Nov 29 Boston @ Orlando
7:00 pm
Wed, Dec 1 Philadelphia @ San Antonio
8:30 pm
Mon, Dec 6 Detroit @ Dallas
8:30 pm
Wed, Dec 8 Minnesota @ Philadelphia
7:00 pm
Tue, Dec 14 Portland @ Minnesota
8:00 pm
Mon, Dec 20 Utah @ Philadelphia
7:00 pm
Sun, Dec 26 Boston @ San Antonio
7:00 pm
Tue, Dec 28 Houston @ Milwaukee
8:00 pm
Wed, Dec 29 Minnesota @ New York
7:30 pm
Sat, Jan 8 New Jersey @ Orlando
7:00 pm
Tue, Jan 11 New Orleans @ New York
7:30 pm
Sun, Jan 23 Miami @ Philadelphia
6:00 pm
Mon, Jan 24 Detroit @ Minnesota
8:00 pm
Tue, Jan 25 Phoenix @ New York
7:30 pm
Sat, Jan 29 Orlando @ Washington
7:00 pm
Mon, Jan 31 Indiana @ Philadelphia
7:00 pm
Mon, Feb 7 Indiana @ Washington
7:00 pm
Wed, Feb 9 Miami @ New York
7:30 pm
Sat, Feb 12 Orlando @ Philadelphia
7:00 pm
Mon, Feb 14 Utah @ Phoenix
9:00 pm
Tue, Feb 15 L.A. Clippers @ Orlando
7:00 pm
Tue, Feb 22 Boston @ L.A. Lakers
10:30 pm
Sat, Feb 26 Indiana @ New York
7:30 pm
Mon, Feb 28 L.A. Lakers @ New York
7:30 pm
Wed, Mar 9 San Antonio @ Phoenix
9:00 pm
Fri, Mar 11 Dallas @ Milwaukee
8:30 pm
Tue, Mar 15 Miami @ New York
7:30 pm
Sat, Mar 19 Utah @ Washington
7:00 pm
Mon, Mar 21 New Orleans @ Dallas
8:30 pm
Mon, Mar 28 Indiana @ Milwaukee
8:00 pm
Tue, Apr 12 Toronto @ New York
7:30 pm
Sat, Apr 16 Sacramento @ Phoenix
10:00 pm
Mon, Apr 18 Milwaukee @ Philadelphia
7:00 pm