Asterisk in windows

Hi all.

Im new to this Asterisk .Well i want to use its sipserver and connect sip softphones to it.Im using windows 2000 server.
W’ll Asterisk is compatible[color=red].Im behind NAT(full cone nat),any issues due to this?[/color]

[color=red]Well if codecs used by the sip useragents are different ,it creates any issues ?[/color]

Please revert back to me asap.