Microsoft included everything you need to get started typing in Russian right inside Windows XP. There is no need to buy additional software just to type in Russian. There is also a handy on-screen keyboard included which can help you remember where all the different letters are located.
All the instructions you need are below, and I also included this video to show you how to set things up.
Step 1: Open the Windows control panel (click Start -> Control Panel).
Step 2: Click on the category “Date, Time, Language, and Regional Options.”
Step 3: Click on the task “Add other languages.”
Step 4: Click the “Details” button in the “Regional and Language Options” (Languages tab) window when it opens.
Step 5: In the window that opens, click the “Add” button.
Step 6: From the “Input language” drop-down menu, choose “Russian” and click OK. Also click OK to close the “Text Services and Input Languages” and “Regional and Language Options” windows.
You should now see the “Language bar” in your taskbar, near the lower right corner of your screen. This bar allows you to switch your input language and also acts as an indicator, showing which language is currently selected. You can switch languages with the keyboard by pressing the Alt and Shift keys at the same time.
If you have trouble remembering where all the Russian letters are located, you might find it easier to use the on-screen keyboard which can be found in the Start menu under All Programs -> Accessories -> Accessibility -> On-Screen Keyboard. While this can be useful, it’s probably better to pick up an English-Russian keyboard or some Russian keyboard stickers for your computer.