Need a new router ... Suggestions?

Yes, thats about what I'd expect a 1721 to do (actually I'd expect a bit less, around 7-8Mbps).

You don't want a router for what setup you give. You want a firewall.

Routers that are designed to carry 100Mbps traffic are in a whole new class compared to the 1721 (desigend for T1 (1.5Mbps) traffic). A 3825 would probably do what you need, but is $9500 list.

Firewalls are designed to forward at 100Mbps rates (or higher for bigger ones), filter, do VPNs, some IPS functions, etc. etc.

The Cisco PIX/ASAs are certainly capable, but I prefer FortiNet or Netscreen firewall products over the Cisco ones. A F60 or F100A would easily handle what you need with plenty of throughput, and a fraction of the price of a router that can handle it.

Thanks for the suggestions guys. Strangely Cisco came back and told me a 1841 with the HWIC 4ESW would be able to handle the 100 Mbps. I am a bit surprised by this but it is much closer to the cost I have available.

Sometimes people recommend router capacity on the worst case of 64 byte packets.

64 byte packets at 100M = 140,000 pps and that is doubled if you use full duplex.

To handle this you need a pretty meaty router, 3825.

This is the absolute safest thing to do.

On the other hand most actual traffic has a much higher average packet size than this. I recently noticed a Cisco design document that mentioned IMIX traffic distribution and used it to size routers.

"1 packet at 1500 bytes, 4 packets at 512 bytes, and 7 packets at 64 bytes." Average of these is 333 bytes.

An 1841 has a much higher performance that your 1721

This says 75,000pps vs 12,000pps.

1841 can sustain 38Mbp with 64 byte packets so to achieve 200Mpbs the average packet size would need to be 200/38 * 64 ~ 350 bytes.

I would give it a go if you are using the internet for a bit of browsing, e-mail, etc.if you are offereing a high volume business service or have a large volume of critical e-mails then I would go for something bigger.