steam connection issues through ISA 2006

ok people before you start attacking the ISA server sucks thing, try to focus on this actual issue please and let me know if you've seen this problem and if you have any good troubleshooting steps

so last week, i uninstalled ISA 2004 on my 2003 r2 member server and installed ISA 2006 Ent. and this is when i started having the issue

my topology is simple, i got a DSL modem, connected to the ISA on a dedicated NIC, then the 2nd NIC on the ISA is connected to a switch which goes into my LAN, ISA is my DSL dialer, router, firewall, and proxy (i don't use the proxy - disabled)

currently for troubleshooting i have left all the ports open and i'm not using any of the fancy features and filters of the firewall, i have another 2003 r2 server which is my DC, caching DNS, internal DNS, DHCP, and IAS Radius server (for ISA VPN authentication), other junk on there is DFS and IIS

the problem: i open steam for hl2 and its mods, i start doing a server list update/refresh, for any game on there, mainly dod:source, first of all i only get like 20% of the available servers populated from the master server list at valve, and their pings are double what they used to be, so before i'd have a server with a ping of 50, now it shows up at around 100

this is only with steam tho, if i just go to the command prompt and ping google, it's 50ms, my downloads and uploads are all the same as they were before i upgraded the ISA, i close down everything and just let steam run from a fresh reboot, same thing, i can launch the games and pull the server list from within the app. of cs:source and i still have the same issue with high latency

i don't know what port steam uses to get the master server list report, no it's no 27015, that's the game port itself...i would assume 80, but i don't know what's wrong with it...any clues why it's so high in latency and why i don't see all the servers?

since i'm lazy i haven't yet tried going directly to the dsl router and dialing out, bypassing the ISA box, my assumption is if i do that i won't have the issue, but i'll try and do it and post the results here

thanks all in advanced