I purchase Benq 1655 and it is bundled with nero 6. So, can i upgrade Nero 6 to Nero 220.127.116.11?
Yes but you will have to buy Nero 7. There is a big difference between an update and an upgrade. You get free updates in Versions, but when you go from Version 6 to Version 7 that is an upgrade not an update.
There is an upgrade path on the Nero site but you can probably do just as well or better by watching the sales (buy.com, techbargains.com, etc.).
(I don't know if the upgrade path will accept an OEM version).