Gigabit Ethernet over Fibre

Hi folks
I need to run Gigabit Ethernet between two buildings. There is an existing 62.5/125 fibre cable between them but the distance as light flies is 483m. I'm about to tell them they'll have to pull in some new cable. But before I do, does anyone know of any kit that can drive Gigabit over that distance on legacy fibre? The proposed network infrastructure at both ends is Cisco 3550 and 3750 switches
Thanks all - and if I'm slow to reply it's because I'm off work now until January but I'm sure I'll be dipping into Firewall.cx from time to time over the festive season...

Exactly which models are you going to use?
If you can install gbics then check this link:
www.cisco.com/en/US/products/hw/modules/...9186a008014cb5e.html
keep us informed.......

Design at present is for Cisco 3750G-24-TS at each end of fibre link. This switch doesn't support GBICs but has SFP plug in modules. The Cisco blurb says the LH/LX variant of these will support up to 550m over 62.5 fibre as long as I use a mode-conditioning patch cable (no problem). However it quotes that distance for a cable with a modal bandwidth of 500 Mhz/Km. I don't know what the modal bandwidth of this cable is though, and I want to be sure this is going to work on the existing fibres before I sign off the design! Alternative, as I said, is to chicken out and tell them they'll have to put new cable in. Any suggestions?