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That router should work fine with Virgin Media cable. It should be simple to set up out of the box. Simply power off the modem and computer (s), plug ethernet between router (WAN) and modem, plug ethernet between router (LAN) and PC(s) or consoles. Start modem, let settle, start router, let settle, start PC(s) / Consoles. Make sure PC(s) browser and network card settings are set to auto. Once you have wired setup, then you can configure the wireless.
For most people the standard firewall in the router is enough. Tweak settings only if you find something can't communicate properly such as torrent software. Then you might need to open ports.
As for wireless you do need to set some security on the router. Ideally enable WAP encryption, if this is supported by your wireless devices, alternatively look at WEP.
As for viruses on the PS3, no idea.