Android update survival, 4" or + screen, 24K budget... Nexus S @21K is the way to go pal.

SE Arc is a super good looking device, but i somehow doubt it getting the 2.4 update officially. I dont quite trust SE on that.
At your budget, y not got for Optimus 2X and put a custom ROM on it. Its far more future proof.. plus you will have access to nVidia Tegra zone on the Android market.

Dell Streak is the smallest tablet with telephony capabilities..

so u might wanna chk it out. Falls within ur budget.
There are loads of problem with DHD... Chk out its review at gsmarena. Also, you will have to use it as a laptop, as it has serious battery life issues.
I would say, wait for a month or 2, the SGSII would come down the price ladder soon, then u can go and buy it with some coupon code at around 28K. Save and collect that extra amount till then.
Correction!!! Anther price drop for Nexus S... Its available for 19K after discount from Letsbuy or 20K from flipkart!!!
Tht just is a killer deal man! Just grab it.