After suggestions for a router that meets my (somewhat complicated) needs and hopefully doesn't cost moonbeams. I'm open to suggestions for VM based solutions as well as hardware.

Currently I have an old cisco router which does everything I want beautifully, except when I try and put my connection under load where upon it starts dying horribly. I suspect it was really designed for crappy slow serial links not me trying to use it on a modern high speed connection :-)

Supports vlan subinterfaces (currently have 4 subinterfaces but would like some room to expand, a dozen would be heaps)
NAT translation and port forwarding (or in cisco land nat overload and static translations)
Multiple DHCP scopes (ie one per vlan) 
Can sustain 100mb/sec across the WAN link, bonus for 200mb/1gb

If cisco's routing performance pdf is to be believed I need to spend a used car for 100mb throughput on the wan, and a small house for gbps.. Help?

In related news anyone ever converted a Juniper ScreenOS box over to JunOS? I have a SSG550M which is running ScreenOS which is being EoL'd and I see no reason to learn it. In theory the SSG550M is the same hardware as the J6350, and only the OS differs.. There's an official conversion kit for a few hundred bucks, but given that its just a replacement CF card with a different OS and a new sticker fro the front I suspect just acquiring another CF card and an OS image would be much easier and cheaper.