does it make any difference what version PowerCLI to use??

We are on ESXi 5.0 U2 and vCenter 5.0 U2.

Does it make any difference which version PowerCLI we use??
If so, how do I determine the currently used version??

And which PowerCLI version matches 5.0 U2 and where/how do I get it??
Thank you, Tom