Can't decide between Asus 1225C and Acer Aspire One 725

Samsung Laptop NP RV513 @ 22.1k only

Already have a Samsung Notebook with 15.6" screen. I want a portable one now.

Consider this :
Samsung NP305U1A-A06IN Laptop (APU Dual Core/ 2GB/ 500GB/ Win7 HB): Flipkart.com: Compare, Review Samsung Netbook

didn't check properly. though it was a 11" unit
if you want a netbook, consider getting one with at least E350 or E450. Even better if you can grab one with E2-1800 but those cost a lot and considering the performance is badly overpriced. avoid all sort of Atom processor cause those are not even powerful for basic multitasking. and ram can't be upgraded.

The Samsung I mentioned above is E-450. Has 2 GB RAM onboard with the possibility to swap it out for higher.
Screen is 11.6 inch but 1366x768.
Lightweight.
Decent battery life. (Just bought it a week back)
-SS.

How about Sony Vaio SVE11115EN ?

Getting it for Rs.25,917 on eBay. Is it worth it?

avoid. don't buy any AMD E/C processor based laptop above 25k. At this price they lose their value as performance wise they trail even 2nd gen Pentium Dual Core. Go for the one sling-shot recommended.
only E-series APU based laptop worth more than 25k is this: Asus U32U-RX012D

Confused

Oh man.. I'm totally confused now. At one point I decide to buy the cheapest one, and on the other point I think I should buy a good one because I won't change it soon.

softwares that run on a E2-1800 will run fine on a 1.6Ghz E450. But neither E2 nor E450 can handle any game or heavy multitasking though basic browsing + office work will go fine. I said at the beginning that E2-1800 will cost a lot and loose their value completely. E2 was suppose to replace E450. instead it made its own section above 25k. Samsung netbook recommended above cost 24k and i guess should be available for 22.5-23k locally as FK is pricing everything 1-2k higher.

with netbook the biggest sacrifice is of processing power. but usually they weight half and offer double the battery life.