If you don't want a high end machine, you can build a low spec machine for next to nothing that will do everything except play games (and burn CD's, print, etc, if you factor the extra cost of the hardware you need for these).
In the UK, you can pick up a good quality upgradable Athlon mobo for £50, a 1 GHz Athlon for about £60, 256 MB RAM (if you need that much) for about £70, cheap nVidia for £25, cheap soundblaster for £10, s/h monitor for £70, keyboard £5, mouse £7, case £30, PSU £20, 40 GB HD £60, CD-ROM £25, floppy £10, Linux for free
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I wouldn't advide renting one personally though...