I can spend only 5-6 days in Uruqmi and its surrounding area, is it worth the trouble ?

Sure! The place is worth a visit! You may arrange your itinerary this way:
Day 1: Xinjiang Museum- Erdaoqiao Bazzar & International Grand Bazzar
Day 2: Red Hill- Water Mill Valley
Day 3: Southern Pastures
Day 4: Dabancheng Wind Farm
Day 5 & 6 : Heavenly Lake- Tianshan Mountains

Hi Julia.
Would there be sufficient time to include a trip to nearby Turpan?
I am a little torn between Dunhuang(+ its vicinity) in Gansu and Urumqi, any thoughts or advice that might help me to decide ? :)
Many thanks.

Sure! You can go to visit Turpan. If by bullet train, it only takes about 1 hour to reach the city. I advise you to go to Urumqi rather than Dunhuang. I travelled there last October, and the scenery was so intoxicating that I didn't want to leave. I can't wait to pay another visit to the beautiful place. You can have a try! May you have a nice trip! :)

Hi Julia,
Thanks for your advice. I am now convinced and shall start arranging for my trip to Uruqmi.
Gansu can be another trip.
Your input is much appreciated, thanks again.