AO721 AMD Athlon II Neo K125 is single core lower power CPU. Passmark CPU score of 489 only slightly more powerful than a 'Netbook Atom processor. This is a very weak CPU and not suitable for the full range of what you want the laptop to do for you.
AO752 Intel SU2300 @ 1.20GHz is a dual core ultra low voltage long battery life CPU. Passmark CPU score of 907 puts in the low range of CPU power but suitable for everything you want to do with the exception of gaming. Just don't expect a fast, smooth multi-tasking system. The weak point of the system is the GMA X4500M HD video chip which won't handle new games on even low settings.
Be sure you read the CCE policies on used/refurbished laptops on refunds, returns and the rest.
Will the GMA X4500M HD be able to play 1080p or atleast 720p youtube? I read somewhere that Flash 10.1 has gpu support but not for GMA X4500M HD, if this is true it would critically affect youtube playback
Also, is there a single core version of the SU2300 because I came across a cpu benchmarking test that listed it under the single core cpu benchmarks
Thnx for any additional insight into this comparison