Sorry to answer questions with questions, but here goes:
What do you consider "High speed networking "
Second, describe the building and the number of users better.
Third, describe any special requirements such as VOIP ( The new network AIDS), wan needs, legacy requirements,
odd protocols.
Fourth Do you have brand preference / are you extremely price sensitive ( are you a cheap p***k? )
Fifth: Do you need a "router"?, Does your situation require/warrant Layer 3 forwarding?
Let me give you an example of three scenarios that I passed through my mind as I read your post.
1: You have a 6 floor hotel and wish to provide "high speed access" to each of the 180 rooms.
Depending on the wiring infrastructure, you buy a Chassis switch with 200 or so 10/100 ports.
place a firewall and a cache / proxy engine on the network, and buy a Cisco 2650 to terminate the T-1 to the internet.
2. You have a 6 floor office building with about 500 users, distributed about 90 per floor with the top floor reserved for conference rooms, etc. Each floor has 2 wiring closets for network, phone etc. Place a 3548 with a Gig GBIC in each closet, home run the 12 Layer 2 switches into a Cisco 6505 with 2 8 port Gig cards and a 10/100 blade.
3. You have a 6 floor design studio that is doing graphic animation on whatever the h*** Unix platform is in fashion this week.
Each workstation requires 1000T , and there are 24 designers per floor out of one wiring closet. Deciding that some blocking is acceptable, Each wiring closet has a 6505 with 2 12 port 10/100/1000 boards and a 4 port 1000 SX blade. All 4 of the SX gig ports are combined into an Etherchannel, and connected into a 8500 in the computer room, where the DWDM box is attached to of-site fiber-channel disks for backup.
As you can see by my simplified responses, there are many different things to consider.
Hope this helps;
Doug