It depends on what you're wanting to use it for... if your work doesn't require the tools of Illustrator, then it's going to seem like a complete waste of money. You don't indicate what type of work you are intending on doing.
I, personally, LOVE Illustrator. I DO warn, however, that you need a system that can accommodate the size of the program itself (over 100 MB, I think) AND the size of the files that will result from your work.
Illustrator is a wonderul tool for doing layouts of work/images that you have already manipulated in OTHER programs (like Photoshop), which is how I use it.... it is also a great program for creating graphic layouts (like posters, brochures, etc.), which I have also done... except on a much more general scale than professional graphic artists.
Also, I prefer using the Adobe creative suite on Mac rather than PC. Believe it or not, although both formats are relatively similar, the Mac versions have some interesting minor things that make for a more refined design approach. But that's probably more about personal preference than anything else.
You could probably do a search regarding Illustrator and find some great sites that demonstrate the work that can be achieved with the program AND a description of system requirements...
Good luck.