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OpenOffice.org offers similar functionality to Microsoft Office programs such as Excel, Word, and yes, Access. It will open and save in .doc, .xls, and .mdb formats - in other words, it's highly compatible with MS Office. It's even more compatible than older versions of MS Office, since it's open source and frequently updated; as Microsoft changes their file formats, Open Office is changed to work with them.
And Open Office is free free free free free.
I installed it recently at the advice of a computer-savvy friend. I love it! My old installation of MS Office had all sorts of problems. Open Office, by contrast, works beautifully with nary a glitch.