HI!

I am from india. I came to US in aug'08, was on F-1 for a year and then now I am on my OPT visa since oct'09 which is good until oct 2010. I started work from dec'09.
I biggest concern at present is the exact percent of tax that will be cut from my each pay check.
These are my questions:
-What are the types of taxes that I am liable to pay from my biweekly income?are there any for which I can choose to not pay. Kindly also let me know how can I do that.
- If I earn $2500 in 15 days, (I calculated this based on an salary of 60 k per year). So how much will be amount of tax that I will pay on each pay check and what will be the amount on my pay check after deducting all the taxes?
-I am on my OPT now and I can get my H-1 soon. But I am thinking I will postpone my H-1B filing for the next year quota because I got to know from some one that if I work on OPT visa I will pay much less taxes than on H-1B. This is my major concern. Kindly let me know.
I know my question asks a lot of information but I am really unaware of all the taxes and laws for non residents. Please give me a detailed information and also other sources where I can find relevant information.

On F-1/OPT you are exempt from residency for 5-years. Your income is not subject to SS tax and Medicare Tax. You pay federal and state income taxes. You must file nonresident tax return and get treaty based deduction. Your U.S. Tax Return: U.S. Tax Filing Requirements for Non-Residents (http://taxipay.blogspot.com/2008/03/us-tax-filing-requirements-for-non.html)

On H-1B, you must pay income taxes and SS tax and Medicare tax.

If you need detailed information and help on filing taxes, please call me at (973) 998-4876.