I expect enormous ratings tonight at 8 when "Two and a Half Men" kills off Charlie Sheen's "Charlie Harper" on the same night Sheen is ripped in a roast on Comedy Central at 9.

That's not to say the show will necessarily be a hit, but the replacement of the troubled Sheen with Ashton Kutcher could renovate an aging but still successful sitcom in an unexpected way, bringing a young audience to the show.

As if "Two and a Half Men" needs a promo, here's one from CBS:

It's just one of the questions about the new fall season which launches in earnest tonight. Some new shows and season premieres have dribbled out, bit this is the biggest week of the new season.

And among the biggest gambles: Are network viewers interested in either of a pair of 1960s dramas, starting with NBC's "The Playboy Club" debuting tonight at 9 on Channel 4. The other is ABC's "Pan Am," which starts Sunday night at 9 on Channel 12.

"Mad Men" thrives with a small audience for that stylish 1960s drama on cable's AMC. It's not clear if that interest translates into the much larger audience needed to support a network show.

Also a gamble is Fox's expensive "Terra Nova." With Steven Spielberg's name on the show (as an executive producer, and an elaborate premiere (not coming until next week on Channel 6), it should premiere well. But it's the audience that sticks around in succeeding weeks that counts.

But the biggest Fox gamble is "The X Factor," which moves Simon Cowell and Paula Abdul to a show that's not dramatically different to "American Idol." It's been hyped like crazy, and its performance will be watched closely.

It starts Wednesday at 7 on Channel 6.

The show I'm most hopeful about is Fox's "New Girl" with the likable Zooey Deschanel. This comedy about a modern day "That Girl" starts at 8 p.m. Tuesday on Channel 6, following ratings powerhouse "Glee."

Here's a little look:

Tonight's new stuff: NBC launches a new season of the a capella "Sing Off" at 7, followed at 9 by the new "Playboy Club," on Channel 4.

• ABC has the latest run of "Dancing with the Stars" at 7 and the return of "Castle" at 9 on Channel 12.
• CBS has two new episodes of "How I Met Your Mother" at 7, followed by "Two and a Half Men" at 8 and the new "2 Broke Girls at 8:30, and the new season of "Hawaii Five-O" at 9 on Channel 58.
• The CW has the new "H8R" at 7, and Sarah Michelle Gellar's "Ringer," which premiered last week, on Channel 18.

Hoping for a stronger "Community" season: NBC's "Community" barely made it to a third season, so the numbers will have to improve when the show returns Thursday at 7 on Channel 4.

The sitcom, from Milwaukee's Dan Harmon and featuring Marquette grad Danny Pudi, is being beefed up with the addition of beefy John Goodman.

Tell you friends, especially the ones with a quirky sense of humor, to be sure and tune in.

Here's one more advance look: