if you are looking to do midi, don't bother with protools. midi support "blows" in it. Also the hardware can be expensive...you can go with the digi001 or the Mbox (as they are designed as entry level units). It you want to take protools for a spin they have a free download of Protools (8 channel maximum) that to my knowledge never expires. would be a nice way to try it out.
Logic is great for midi, but as stated, apple have purchased Emagic and as of the release of 5.2 there will be no more releases, bugfixes, etc etc etc for windows. so if you want software that will continue being supported and developed, skip it.
I personally use Cubase on my mac, but if i were to use a PC i'd be all over Cubase. The next "point release" should bring with it VST System Link, so later on down the road when you need a computer with more punch, you dont' have to ditch the old one...you'll be able to load balance between the two. SX is based on the nuendo audio engine and i've heard that audio editing is leaps and bounds beyond the "minimalistic" implimentation in 5.x (VST/32). Steinberg should have demo's posted. if you want to try out SX.
I've never used Sonar. i tried Cakewalk years ago and i just couldn't get into it. cubase has always been much more logical to me. [shrugs]
as for hardware multitrack recording, ummm, if you enjoy little lcds for editing, have at it....otherwise be prepared to pay out some $$$ for the nicer units. i've personally always been a big fan of the Roland VS systems. you could probably find a used VS840 or VS880 on ebay for fairly cheap.
as for $$$$: Cubase SX i think is $699, audio interfaces for a computer range from about $300 up to...well a lot, Roland VS840's i think are selling used for around $400ish, it's all a matter of what interface will be the most comfortable for you in terms of working with audio. i like a nice mix of hardware (synths, samplers, analog console, hardware fx, etc) and software (Cubase, Rebirth, etc)
good luck.