Q I would like to find a way to use two distros at the same time without rebooting. Is there a program that allows a user to boot up another distro when already in another? For example, if I had a dual boot PC running distro A with distro B installed on a separate partition, would there be a way to boot up a distro B session while running distro A? If so, would there be any issues such as latency and responsiveness?
A There are several options for this, most of which involve some sort of emulation. Which one you choose depends on how much effort you want to put into it, and whether you want to spend any money!
The easiest, and most expensive, solution is the commercial VMware Workstation 5. Although often perceived as a means of running Windows on Linux, or vice versa, it is very good for Linux on Linux and is how I test software on various distros. The VMware website is at www.vmware.com. This is a virtual machine that does not try to emulate a processor, so it achieves near native speeds.
The next alternative is Qemu. This started life as a processor emulator, but there is an accelerator module available now, which turns it into a VMware-like virtual machine when emulating a PC on a PC. It's slower than VMware, even with the accelerator, but it is free, and could be ideal for your needs. Qemu is available from http://fabrice.bellard.free.fr/ qemu. Qemu is open source, but the accelerator module is only free as in beer (it's proprietary).