Some more information from my visit to Lamington Road today
Model OS Cost 4736 Linpus 32.5K 5738 Linpus 33.5K 5536 Linpus 26.5K
The prices are from Yoku Computers. I confirmed with them, hardware warranty is still valid irrespective of the OS you use on these machines. So, you can install your favourite distro on it without worrying about warranty. 5738 looks like a good deal, and considering that ubuntu worked out of the box for my friend on 4736 and it not being too different from 5738, the latter sounds like a good deal.