I'm pretty sure that StarOffice / OpenOffice support excel spreadsheets well.
They're both damn good office suits. I believe that StarOffice 5.2 is available to download from Sun's website, and OpenOffice is available from OpenOffice.org
. I think that StarOffice 6 will look more like OpenOffice (i.e. they will have dropped that awful start-bar - I'm sure it's useful if you're using BlackBox or the like, or if you're using X with no proper WM, but I think it's awful when used with KDE).
BTW, does anyone know where to get a copy of StarOffice 6 Beta?