it's all a matter of preference and situation, really. if you're recording live as a full band, either in a gig or studio situation, it might be better to go with a workstation. they have multiple ports and channals for multiple players at the same time and they have zero latency issues. Many even have nearly unlimited track capabilities now, both virtual and real. You might be more limited with editing and mixing with a workstation.

however, a fast and powerful new MAC or PC laptop can offer the ability to host a multitude of programs such as Reason 3.0, Battery, Amplitube, ProTools and many many many more programs. Plus, you get upgrades. They're customizable and generally very dependable now that, with faster processors, latency isn't really much of an issue. One very important thing to remember with a MAC or PC laptop is that it should be 100% totally dedicated to recording. That means NO INTERNET what-so-ever. Nothing will kill a recording setup on a PC or MAC faster than webjunk. Trust me... I've had more than my share of personal experience with this matter. Also, you get more mixing and editing capabilities. Most recording software comes with a very broad-range virtual EQ board so you can get any sound you want. Also, you can plug workstations into laptops. I'd suggest a firewire connection over a USB connection, though, because USB's tend to be slow and can cause latency issues sometimes.

uh...both?

record with a decent system then put it on your computer for editing. 

Been recording with both a digital 8 track and mix/tweak etc with a PC.  Seems to offer a good solid combination for what I do (I record by myself).  I write my tick and drum track and maybe a bit of strings or whatever on the PC controlling a Yamaha MOTIF Rack ES that gets recorded to a PC, then pump it over to tracks 7-8 on the 8 track and go from there.  Then export back to the PC running Audacity, clearing more tracks on the 8 track if needed.  Everything gets mixed down and burned to CD on the PC.

Everything is on a budget except the wad I blew on the MOTIF, but hey, it's a great synth! Using the 8 track while playing guitar/bass/whatever is easier than a keyboard and mouse while handling guitars, as I mentioned, I work alone.  Yeah, I'm THAT SHY!  ;)