how much Mbps for 2 computers?

Torrent downloading can max out ANY speed of connection. Get whatever speed you can afford, but set aside some money for a GOOD router than can do QOS.

You have to prioritize the gaming packets, and de-prioritize the downloading. That way, your games will always work and even web browsing won't be slowed down by the browsing.

You lose a little bit of your speed when yo do QOS, because it has to reserve some extra headroom for overages. It has to make absolutely sure that your connection doesn't get maxed out.

Omnichad is correct, no matter what speed you buy, torrents and other downloads will always bog down your gaming unless you have a router with QoS that can prioritize traffic by either port (your machine) or by the type of traffic.

I have 10mbps download, and downloading torrents for Debian distributions, any online game becomes slower. However, if I limit the torrent to 9mbps download limit (and limit upload), my games work just fine, because I've reserved that 1mbps for "other" traffic.

If you want to download at a decent speed and still be able to game without major laggs, I would suggest 10 MBit/s and up.

You never state how many Mbps :O

But obviously it would be half of that connection for each computer.