When it comes to boffo openings, forget "Pirates of the Caribbean" -- think "Grand Theft Auto IV."

And think $400 million for the first week, a record for vidgames and possibly the biggest debut ever for an entertainment product.

Sources close to publisher Take-Two Interactive, whose Rockstar Games label is developing and releasing the title, said that the latest installment of the hit franchise will reach that figure and sell some 6 million units after it launches worldwide on April 29.

Though they rarely release the data, videogame publishers are able to accurately predict early game sales based on what retailers order.

Microsoft currently holds the record for the biggest videogame launch with "Halo 3," which grossed $300 million in its first week and sold about 5 million units.

"GTA IV" has even bigger potential, however, since it is available for both the PlayStation 3 and Xbox 360. "Halo 3" was an Xbox 360 exclusive.

Several industry analysts also told Daily Variety that they fully expect "GTA IV" to come close to and possibly exceed $400 million in sales out of the gate.

Vidgamer sellers have slightly varying predictions at this point, though all expect it to be huge. Blockbuster CEO Jim Keyes said that "GTA IV" will likely do "two times the volume" that "Halo 3" did for his chain, while GameStop senior veep of merchandising Bob McKenzie said the game is currently tracking slightly behind Microsoft's three-quel.

A Take-Two spokesman declined to comment.

The "Grand Theft Auto" series has traditionally done very well in the U.S., Canada and Europe but been somewhat weaker in Asia, the other major videogame market.

Comparisons to other media are difficult, since "Grand Theft Auto IV" costs $60 domestically and contains dozens, if not hundreds, of hours of content, whereas the average film ticket in the U.S. last year cost $6.88 and is good for a few hours of entertainment.

Nonetheless, Take-Two will likely be crowing that the perf of its game is close to, if not above, the No. 1 film bow of all time, "Pirates of the Caribbean: At World's End," which grossed $404 million worldwide in its first six days.

News comes as Take-Two's board is trying to fend off a $2 billion takeover attempt by Electronic Arts. Executive chairman Strauss Zelnick and CEO Ben Feder are sure to be touting early sales momentum for "GTA IV" at the company's annual meeting Thursday, which is, not coincidentally, a day before EA's tender offer to shareholders expires.

Take-Two management needs "Grand Theft Auto IV" to have a huge opening to keep up, if not bump, their company's stock price and justify their advice that shareholders reject the EA proposal. Some analysts have urged them to accept it, as EA is offering a 64% premium over the publisher's previous share price.

Boffo sales for "GTA IV" are widely expected and already priced into Take-Two stock.

Though it's clear that early sales for the game will be huge, it remains to be seen if reviews and buzz will drive "GTA IV" to ultimately perform as well as its predecessors. The franchise's last entry for consoles, "Grand Theft Auto: San Andreas," sold a healthy 21.5 million units, making it one of the most successful videogames of all time.