Max number of VLAN interfaces

Is there a limit on the maximum number of VLAN interfaces that can be
created on the same ethernet interface ? Would it work with 45
(forty-five) VLANs on the same eth ?

I'm asking this because I have to provide Internet access to a
building with about 45 rooms and I have to make sure there is no way
to access the LAN of one room from any other room, so I was thinking
of using an Allied Telesyn Managed L2 switch with 48 Fast Ethernet
Ports and a Gigabit uplink, wire each room to a switch port, setup 45
tagged VLANs, and hook up a Linux router to the Gigabit port. The
router would have 45 vlan interfaces and routing / iptables SNAT
should take care of the rest...

The Internet connection will be wired to another eth interface on the
router (2 Mbps for start, soon to be upgraded to about 20 Mbps).

Also, off-topic, but does anyone have any advice on the hardware
requirements for such a router setup ?

Thanks in advance !