There are alternatives:
1.) Consider the free alternative to MS Office, OpenOffice.org. OpenOffice is compatible with Office file formats, such as Excel. But if your laptop only has 346 MB of free space, that's probably not enough for OpenOffice.
2.) Another alternative is to use Google Docs. Excel files can be uploaded to Google Docs and shared:
"Upload your existing files. Google Docs accepts most popular file formats, including DOC, XLS, ODT, ODS, RTF, CSV, PPT, etc. So go ahead and upload your existing files."
More info at http://www.google.com/google-d-s/tour1.html
3.) If Google Docs isn't your taste, enter "web based office suite" into your favorite search engine.