XP small network

[Capitao]

Hi,

I have my network like this:

ISP ---- Cable Modem --- PC1 --(cross-cable)--PC2

Hi have internet in both PC's with XP, I setted it up with the windows network wizard. PC2 can surf, send and receive mail and instante messagens, but can't send instant file througth messenger, also it can't establish a conversation using messenger. PC1 can do all this. PC2 is using the internal ip, so can't establish direct connections to any PC outside the network, is this possible to workaround? How?

Thanks,

Acácio Jesus