Guys, is 120GB SSD enough space for Primary OS for Win 7, normal programs & run few games?

Absolute fastest 60GB SSD now is the Samsung 830, but that might be quite hard to get and is quite pricey.
For much less of the cost and almost as fast as the Samsung 830, you can't go wrong with the Intel 330 or Crucial M4.

Other Sandforce based SSDs (other than the Intel 330) are like the Mushkin Chronos (cheapest 60GB asynchronous SSD out there now I think, under RM250 can get), Corsair Force 3, OCZ Agility 3 and so on.

My suggestion, if you can.. go with the Intel 330, RM280-RM300 is a great choice as Intel's reliability is legendary (there aren't a lot of error reports from 330 users thus far yet).
Unlike other SF based SSDs under the RM300 mark, Intel uses synchronous memory instead of asynchronous like other cheaper SF based SSDs.

Otherwise, the Crucial M4 is a great alternative too.