I am currently in F-1 status but applying for 2010 H1B visa (Waiting for decision).
I plan to marry a green card holder by early next year.
Once married and applied for green card, do I HAVE TO remain in F-1 status or H1B status until I get final decision about my green card? Or can I become automatically in green crad status? Or something else?

The preference classification for this is FB-2A. Permanent residence as the spouse of a permanent resident is a 2-step process.

(1) after you get married, your wife files the I-130 relative petition, this creates the priority date (your place in line for an immigrant visa--green card) then you wait until your priority date is current. As of today it is about 5 1/2 years, then (2) you file for your AOS. At that time you can file for an EAD to work while your application is pending.

You will want to keep your H-1B status during this time, as it will allow you to stay and work in the US until your PD is current.

I trust this is responsive to your inquiry. Congratulaitions and good luck.

Maintain your non-immigrant visa until you get GC, anything could happen during these five years.

Your spouse may file an I-130 for you as soon as you get married. However, because your spouse is a PR and not a Citizen you will have a long wait to get your green card - so mainain your visa while waiting. Your spouse needs to apply for citizenship as soon as possible. When he/she gets citizenship your I-130 can be amended as filed by a citizen instead of a PR. Once the petition is amended as filed by a citizen your wait will be reduced to months rather than years.