Going from a 1.66Ghz Atom to a 2.0Ghz Atom CPU would be such a minuscule performance upgrade it's just not worth the trouble/cost.
The upgrade to 2GB of RAM, on the other hard, might be a worthy upgrade and cost about $50-60. 4GB? Again, probably not enough of an increase in performance over 2GB, given that Atom single core CPU doesn't multi-task well, to make it worthwhile.
Any 2.5" 9.5mm thick laptop HDD drive should work OK. Just check that the power requirements are the same spec.
Note that the 532h has an available a free mini PCI-e slot which can be used for upgrading, perhaps a Broadcom Crystal HD Accelerator.