I'll also vote for 'do what you love' .. it is the only way to ensure happiness.
Now, you're lucky enough to love doing something that opens a lot of doors. Computers are the future.
As for what career path you should take, I think you should keep all your doors open. You won't be entering the workforce for another 5-10 years and in this industry, everything can and will change in that time. When I started by BCompSci, the industry was dying and everyone said that there would be no jobs when I graduated .. and they were wrong.
So .. I'll give you some general advice:
If you like hardware, you can either design it or install it.
Installing and configuring PCs in a corporate environment can get you a decent paycheque and there will be work in the field. It requires a college diploma or some certs, but you don't need a degree or extensive schooling ... experience is more important for this career path.
Designing hardware is a more difficult career path that requires a degree in computer or electrical engineering. Here, you'll spend most of your time in front of a screen designing new hardware and testing it. Your math and physics need to be very strong and you should have a solid understanding of how computers work.
If you like software, you can either design it, test it, or install and administer it.
Designing / writing software is the basic 'computer programmer' job. You will need a degree in software engineering, computer science, or something related. Your math and logical analysis skills need to be top-notch. You can make good to terrific money doing this, depending on your skills and your willingness to work.
Testing software is often an entry-level career path to programming, though many (including myself) think that this is an industry-wide mistake. Testing software and writing software are different though related skills. You don't NEED a degree for most testing positions, but you will need one if you want to advance in the company. This is a great career path for people who like breaking things, taking them apart to see how they work, and bugging programmers when they find yet another bug.
Installing and maintaining software is the last path I'm going to discuss. This type of career (System administrator is a common title) is very common and very easy to find work. You don't write software; you maintain the servers, applications, and PCs that are used by a company.
This ranges from administering an internal network of PCs in a small company to a huge network of networks (such as on a college campus). You could also find yourself admining networks used by large corporations such as AOL, MS, Google, or eBay. After all, eBay and MSN and all the other online services that you use always have someone sitting in front of a bank of monitors, watching and ensuring that everything is working properly.
Skills necessary for this career path include in-depth knowledge of operating systems (MS, Solaris, Unix are the most common) as well as the scripting languages (shell scripting and perl are good to start with) that glue the networks together.
You're 15. I suggest getting your feet wet and trying to get summer jobs and part-time jobs in as many different 'computer related' fields as you can over the next couple of years. The only way to figure out what you want to do is to do stuff and decide if you like it.
You'll be spending a minimum of 5 days a week, at least 40 hours, doing for years ... so take your time and choose well.