two servers or one?

i ordered a dsl-flatrate ot connect my lan to the i-net. the lan consists of three pc's, two with windows98/linux and one with windows98. i have on old P-120, 64MB Ram adn 2GB HDD which i would like to use as a proxy.
is it more secure to run apache and samba (with encrypted filesystem) from another pc or is it quite save to run these services from the gateway, and are the resources of this pc ehough?

personally I would run it on a different computer, to save resources for a good proxy/firewall. But thats just me.