PortableApps Suite Light
If you want an all-in-one package of basics--spreadsheet, word processor, graphics--you can have them all completely free. An excellent collection is Portable Apps, which comes in two sizes, Standard (260 MB installed) and Light (105MB installed). Both versions include antivirus, a Web browser (Mozilla Firefox), instant messaging (Gaim), a Sudoku game, a calendar and task manager (Mozilla Sunbird), and an e-mail client (Mozilla Thunderbird). The Standard version also includes a portable version of the OpenOffice suite, while this Light version comes with AbiWord word processor instead.
Note: This link takes you to the vendor's site, where you can download the latest version of the software. This suite is donationware. It is free to try, but the authors accept and encourage donations towards further development.