So you finally made the jump to Ubuntu and now have a Ubuntu Computer. First of all, congratulations for making the jump! But you realized you will not be able to run your favorite Windows programs you've been using for the past several years.
No problem. There are 2 things you can do to ensure you'll still be able to use Windows programs on your Ubuntu computer. The first thing you can do is run a "dual-boot" system. This requires you to be able to use Ubuntu and Windows XP on the same drive. When you want to use a Windows program, all you have to do is shut down your computer and reboot to Windows.
This is made possible by the bootloader located in Ubuntu called "Grub". It allows you to install onto the same hard drive as a previous Windows installation. You have to create the disk area (or partition) to load Ubuntu and make sure it is separate from the Windows installation. Once you do that, you can install Ubuntu without affecting your current Windows partition.
Another thing you can do is run your Windows operating system in "virtual mode" within Ubuntu. This means you can run the entire Windows operating system inside Ubuntu without requiring a reboot. This allows you to use your favorite Windows computers without rebooting since the Windows operating system is running in a separate window.
What are some good programs you can download that allow you to run Windows in virual mode within a Ubuntu computer? A good one is called Virtual Box by Sun Microsystems. You just install it and install your Windows installation within the program. It isn't really too hard.
Of course, the best way to have a Ubuntu computer that runs perfectly is to have "replacement" programs that take the place of the Windows programs you used a lot. There is an open source program for almost every Windows program out there. There will be some "adjusting" as you get used to these new programs on your Ubuntu computer, but you'll be able to run these programs natively which will be a LOT faster on your system.