Routing Suite in an ISP environment?

Searching for an alternative for our old Cisco Border Router we are evaluating some software routing suites on "normal" server hardware.
First we tried Vyatta, but the routing software frequently crashed completely. Maybe this is fixed with VC4 Alpha 1, but we didn't test that.
Next try was the development version (0.99.9) of quagga from Debian testing, but it looks like a peering with one of our cisco router fails after the hold timer expires.

2008/02/19 15:08:06 BGP: Performing BGP general scanning
2008/02/19 15:08:06 BGP: scanning IPv4 Unicast routing tables
2008/02/19 15:08:06 BGP: scanning IPv6 Unicast routing tables
2008/02/19 15:08:07 BGP: Import timer expired.
2008/02/19 15:08:13 BGP: 192.168.96.2 rcvd UPDATE w/ attr: nexthop 212.202.214.150, origin i, localpref 100, metric 0, path 20676 2914 2914 2914 2914 4755 4755 4755 4755 4755 9583
2008/02/19 15:08:13 BGP: 192.168.96.2 rcvd 124.7.35.0/24
2008/02/19 15:08:13 BGP: Zebra send: IPv4 route add 124.7.35.0/24 nexthop 212.202.214.150 metric 0
2008/02/19 15:08:17 BGP: 192.168.96.2 sending KEEPALIVE
2008/02/19 15:08:17 BGP: 192.168.96.2 KEEPALIVE rcvd
2008/02/19 15:08:17 BGP: %NOTIFICATION: received from neighbor 192.168.96.2 4/0 (Hold Timer Expired) 0 bytes
2008/02/19 15:08:17 BGP: %ADJCHANGE: neighbor 192.168.96.2 Down BGP Notification received

Any ideas are welcome ... also some other routing suite alternatives.