keaki

hi everyone, i have a friend who has screwed up my computer and apparently put in a 32 bit polish edition which has clashed with the 64 bit edition that i had, can you please see if you can help me and find somewhere where i can get a 64 bit edition and reinstall it so that i can finally use my computer which has only just come out of the box i have got an athlon 64 bit 3400+ cpu, 2x 512mb pc3200 ddr ram , 200 gb