How to upgrade Google Nexus one phone from Android version 2.3.1 to 2.3.3

Hello There,

Can you please help me to upgrade my Google Nexus one handset from Android 2.3.1 to 2.3.3? Here is what I have in my phone.

Device: Google Nexus one
Carrier/Network: Vodafone (India)
Android Version: 2.3.1
Baseband Version: 32.50.00.32U_5.12.00.08
Kernel Version: 2.6.35.7-59410-gba07db7 android-buildapa26#1
Build Number: MicroMod v.20 (AOSP GINGERBREAD 2.3.1)
I brought this phone from USA. I am using from India.

Also I am getting system updates on my mobile i.e. "Nexus One update to Gingerbead MR2". The file size is 87.6 MB. I can't update, download failed.

I want to upgrade manually.

Any help would be appreciated.

Thanks
SP