I would use an op-amp with FET inputs such as this dual one that can be run from a single +5V supply http://www.farnell.com/datasheets/76675.pdf. Or you could use the widely-available TL081, but then you would need to provide a -5V supply.
EDIT: I just read the following in that article I linked to: "Use instrumentation amplifiers with very high common mode rejection ratios on the order of 100dB".