2PC's can not see each other - sharring files

I have to pc's I want to move files from one to the other. One is a XP Pro
SP2 box and the other is Windows Vista 64 Ultimate. I have a linksys router
and both are connected and have ip's. I have a folder on each C drive sharred
and neither pc can see the other when I goto map drive. I looked in linksys
DHCP client table and see both pc's but only one the Vista pc has a client
name the other is blank. Not sure if this is it but the XP box does have a
name.

When I ping from the Vista box the the Xp box I got no replys at all for all
four, 100% loss. From the xp box to the Vista box I get replies 0% loss.

How do I fix this issue. Please help.

Thanks