Sorry didn't realise you were PC only... yes, Logic is Mac-only - that's it's only requirement... but is awesome in comparison to Cubase (especially Mainstage)
There is a version of ProTools that requires no hardware but it's generally pants...
ProTools on Mac or PC - various versions and ways to do it. But yes, there is a master software component... Protools 8... which will run with any ProTools hardware... but you definitely need the ProTools hardware to get anywhere with it (see
Pro Tools|HD Core Systems) - generally need a core interface card, and then an external interface to give you the I/O sockets to plug stuff in to. Or head down the full blow route of ICON hardware (ie: fully digitised ProTools-enabled Mixing Console with ProTools hardware included within)
ProTools M-Powered will only work with M-Audio hardware.
Here we have an iMac based music suite, all fully integrated to AD via our X-Server, on our RM-CC3 domain, running Garageband and Cubase Studio 4... mounts students and staff's Home folders from the PDC, and mounts various dedicated shares on the X-Server for Music Dept only. The X-server deals with locking down access to apps etc. Kids work and save locally then drag n' drop to their network home or to the X-Server shares. The network hardware from X-Server to iMac is gigabit all the way (all MAC equip on same switch), so when iMacs communicate with X-Server they do so at speed, and uplink from that switch to our coreswitch where all the AD servers are located is also gigabit all the way (over fibre).
We also have a PC suite running ASIO4ALL for regular onboard audio, and they all run Cubase SX3 with Halion for soundbanks - all are RMCC3'd... but this suite gets little use these days.
Both suites use eKeys 49 keyboards. None of our suites use any external-hardware MIDI modules for sounds - everything done using VSTis, usually Halion...
In the recording studio we have a standalone PC running WinXP, with 2x MOTU 8PRE firewire interfaces (for 16ch simultaneous input via directouts on a Soundcraft LX7II console), with Cubase SX3 and Cubase Studio 4. Armed to the teeth with all the Native range of VSTis.