The biggest obstacle will be find something with a newer processor (Core i3 probably.) Don’t get hung up on RAM or hard drive size as those are easily upgraded in the future if you need (make sure you know the max capacity for RAM) and fairly inexpensive.
Those are good specs for the price, but it is refurbished. I don’t like buying refurbs, but that’s just a preference. I know people who have, and have had good luck with them.
I only buy refurbished computers for myself and I have bought dozens of them for companies as well. Every one I have ever seen has been indistinguishable from brand-new just cheaper. I suspect that most of them really are new but were just an ordering or shipping mistakes.
I would recommend getting an intel processor. I5 or higher preferably.
I3’s are cheaper, and are fine for most people, but i5’s will last a while. If possible, also get one with an ivybridge processor. (Not sure if it’s possible to get an i5 ivybridge laptop for 400$).
do you get to keep the laptop? It might just be a better idea to add your money onto the 400 straight away, rather than upgrade afterwards. At least in terms of getting a good processor and such, the economies of scale the big companies have can’t be beat.