Newbie Q. PHP 5.3 vs 5.5

I can get hosting:

5.3 + .asp (linux, windows) = $10 a month

5.5 + .asp " " = $30 a month

Plan to learn/experiment with both... but $480 over 24 months its worth  asking...

How damaging would it be to go with 5.3???

Any wisdom.. ty