I'd second mandriva, but also the fact that a few spare partitions
to try other distro is good (main one for newbee Mandy, Suse, Kubuntu,
PClinuxOS, Fedora core 5 ...
I have a big collection of Excel/.xlm files
Posting about that really.
OOo Openoffice great.
If you found really that for some reason something odd cannot
be read by OOo look into wine (google winehq + linux)
If really desperate you can use xls with linux