* GM car sales in China jump 28.8 pct in 2010
* Borders shares slide a day after two top execs resign
* Futures up: Dow 33 pts, S&P 2.9 pts, Nasdaq 5.75 pts (Updates prices, adds Borders)
By Rodrigo Campos
NEW YORK, Jan 4 (Reuters) - U.S. stock indexes were set to continue their upward trend at the open on Tuesday as optimism continued to permeate the market