There are several ways to do this. What is it you want to do? Access resources on two VLANs that otherwise have no L3 connectivity between them? If so, then the host can access resources by either dual NICs with two switch port connections (easiest way) or possibly using a trunking-capable single NIC and tagging the switch port for both VLANs (more elegant but requiring a bit more complex interoperability - see Hpotential NIC trunking complatibility factors outlined in: http://www.cisco.com/en/US/customer/products/hw/switches/ps700/products_tech_note09186a00800a7af0.shtml ?
).
Routing per se is not necessary. That is, you don't need to move information between the VLANs. You may need to (or want to) put a static route in the host to have it not get confused about how to reach the respective IP subnets.
Is it secure? Well, depends on what you want to secure against. Any (yes I mean ANY) host can be compromised given an adversary with the motivation. However, a properly patched machine that is conservatively (or austerely - depending again on what you are securing against) configured is safe agaisnt the run of the mill script kiddies and bot/zombie crap on the Internet today.
