Bala,
If you have Windows 7 Ultimate with bitlocker already enabled, then I would say you are all set. FIPS compliance is nice and I do recommend it, but you should save it for your next upgrade.
Regarding Windows 8, no need to jump on that now. Stick with your current upgrade schedule. Perhaps wait for Windows 10 to come out then go with Bitlocker with FIPS.
JamesNT