I was on OPT from Jan till sep 30 2007 and on h1 status since Oct 1st. Should I file taxes separately for F1 and H1 visa statuses?

No, you will file nonresident tax return and report both incomes. YOu will also file form 8843.
For 2008, you will file nonresident tax return.

For filing you can take help of AtlantaTaxExpert at [email protected].

Actually, for 2008 (filed in 2009), you will file as a resident alien.