Even a 入門者 (nyūmonsha, entry-level learner) of Japanese can use a personal computer to his or her advantage, as a supplementary learning tool. Most of today's Windows and Apple PCs running English (or other) operating systems can easily be set up to enable 日本語入力 (Nihongo nyūryoku, Japanese input), without requiring extra outlays.
Once Japanese input is enabled, you can access it while running most applications (word processing, browser, mail, spreadsheet, etc.) by toggling the PC from the default language (English or another language). Native Japanese PCs with dedicated keyboards feature a toggle key marked 半角・全角 (hankaku, zenkaku) to switch input between 1-byte (hexadecimal) and 2-byte (Japanese character set).
In Apple computers with English keyboards this is performed by pressing the space bar and "Command" key simultaneously. You can visually confirm that the computer is switched to the Japanese input mode when the status line at the top of the screen replaces the U.S. (or British) flag (signifying English) with the hiragana あ (a).