If budget is a big hurdle for you, PC would be a better choice. If you're those tinkering kind, you may want a self configured (maybe even self assembled) PCs. Otherwise, if you just want to get down to work, buy a PC from a shop that you know will provide service and support.
If you're willing to stretch your $$ a bit more, get a top-of-the-line system, with real time video editing products. Umm.. in this case S$3K may not be enough though.
This is a bit out of my league, so perhaps professionals in this field can advise.
Me? I'm just a normal home user struggling to understand and working with colour management Still haven't bought my system to capture and edit/cut VCDs of my home videos.
I think you'll have to list down your requirements, and needs, project it over a few years, and see if you can reach a compromise between budget, performance (yours) and features (the machine). Tough.