Connecting Homegroups Win 7 and Win Vista for file sharing

Hi. My First post. We have a new HP lap top running Win 7 64 bit, A new Lenovo Think Centre running Win 7 32 Bit, connected wirelessly to my router. Have set up a Homegroup between these two computers and they work OK, My problem, my older PC running Win Vista 64 bit is connected to the same Netcom NB6 plus 4w adsl2 router via a wired connection, this PC has files I would like to share ...