Two isp routing

I have two ISPs. I didn't plan on getting two ISPs. I've had one for ages that I'm reasonably happy with that I've shopped long and hard for. It gives me a static IP and doesn't charge too much. It has a 1Mbps down and 370Kbps up.

Then my son wanted to vastly upgrade our connectivity and our existing link just couldn't fill the bill. So we got another. His link is 30Mbps down and 3Mbps up. I want some of that. But I don't want to disrupt the existing services on my static IP and the original link.

My routing table looks like this now.

root@weasel:/# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         216.99.216.1    0.0.0.0         UG    0      0        0 eth0
10.0.0.0        0.0.0.0         255.0.0.0       U     0      0        0 eth1
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eth1
216.99.216.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0

So I'm going to add another gateway (faster link) and make it the default, but leave the existing gateway. Do I need to give it a higher metric?