I would just get a separate computer all together. Make a perfect one for work and then have an emachines or cheaper dell model for internet/testing. I do this and I never have to worry about anything I can always just format everything. Just think the time you put into doing what you are talking about will cost more than to do it with a separate computer. You could even just get a seperate tower and unplug the monitor everytime you want to switch computers. Hopefully you will be doing more work than play so this won't be a bothersome. Adios, Joe
If you don't like the mac's you can go with a shoebox sized computer called the shuttle. They are very stylish also. http://us.shuttle.com/
I like the true security of my trading system being 100% invulnerable to my other PC. I take risks with my other setup, but my trading system is used carefully. If I DL something terrible and my other PC loses everything and is down until I have a few hours to restore it, it's no big deal. So what if I can't play some games or watch some DVD for a few days or even a week until I fix it? But my trading PC can't be down that long. If I DL some brand new trojan to my other PC, there's nothing it can do to steal my password to my trading account, because I never log in from my other PC, and the trojan cannot copy itself to my trading PC. It's just a basic double pole slide switch, you can get em from Radio Shack for a couple bucks. The basic principle is to have power running to one drive or the other, but not both. That way, there's no way the other drive can be booted, written too, read from or erased. I obtained a couple of power cable extenders. They run a couple bucks each or so, I bought one on eBay. Then I wired it so the switch directs the yellow and red power wires to either one drive or the other, and connect the grounds (black wires) straight to the respective connections on each of the drives. I ended up with a switch that has a plug for the power supply cable and a plug for each of my two drives. Then I cut a hole in one of the front panels in my PC and bolted the switch in. I used long bolts and anchored the wires to them to help out the soldered connections to the switch (was worried that they would break after time). The biggest potential problem is if the switch is changed while the computer is writing to a drive. Not sure if it would destroy both drives or not, but it couldn't be good. I am not responsible for what happens to anybody's computer if they try this. If you burn down your city, don't come crying to me. BTW: A fast way to do this (that I did for a while) is to simply swap the power cable from one drive to the other. If you have a tower and keep your case open, it only takes a moment.
You can hack wire 23 of the IDE cable with a switch to toggle between 2 drives or turn a drive on and off without powering down. Here is an xbox hack using the same principles. http://www.xbox-scene.com/articles/3ide-2dvd-1hdd.php
Uhm, what about when the system is saving your new awesome trading strategy that will make you millions to sector 3124 and you throw the switch? Does the OS suddenly say "Woah, this guy switched hard drives on me"? Is this a common occurance, enough to program for? I bet your xbox thing is for read-only stuff. Hard drives are read/write. And what about disk cache and where the memory cache is, and God only knows what else. This is way worse than my solution.