You need to do 3 nights butt-in-bed, but you might want to manage without...

Due to rollover, you've exceeded your 10 night silver requirement by 37 nights, so that will rollover to 2012. If you have even a basic Marriott credit card you'll get 10 nights credit in 2011 for that which will bring you up to 47 nights. 3 nights in a Marriott later you'll make Gold and that will then last till end February 2013.

If you just squeak Gold this year you'll only have it till Feb 2012, unless you can slog out the 50 nights to renew in 2011.

If you dont have a Marriott card then get one early next year, the US offers are very good for the annual fee one, which I think gives free nights, 15 nights credits and enhanced points per spend, and ability to earn nights credit with spend too. The free ones (such as ours in the UK) give 10 nights stay credit and points on all spending (double on Marriott).

You may find in any event that Marriott grant you Gold status for 2011 anyway, as you're so close, they used to do this before the rollover initiative, dunno if they still do, but as pointed out above that could be a bit of a poisoned chalice...