I don't use Guildftp, so can't help.
All I can say is that I connect to BB via a router and firewall. I use a product from Ipswitch called WS_FTP LE, which is the free version of their WS_FTP PRO.
I installed it and connected 1st time
It's available from click here just scroll to the BOTTOM of the downloads page and click the try it link. I use it on 98SE at work and XP Pro at home.