Respectfully I would do the larger and fastest supported ram the netbook will allow first. The SSD will boot. open programs and close faster but I would see if your sister notices enough speed improvement with just the ram. Use this ram/memory adviser to see what your sisters netbook will upgrade to:
DDR3, DDR2 and DDR RAM memory upgrades from Crucial.com
I think this is a good approach. RAM first and see what happens. 2GB should be plenty for Starter. The problem now is that you get too much paging. That really, really slows a system down.
Regarding the SSD - recently they had 60GB OCZ SSDs on sale (at Newegg) for $38. They were refurbished but OCZ is a serious company and they are probably better than new. You just have to shop around.
But if you think your sis can live with 32GB, that's OK too. My wife lives with little disk space too. But she has all her files on 32GB USB sticks.