Excel doc repair

[htvan]

G'day guys,
I had to use the system restore on my Dell PC. To sort out an issue with the sound card. However I forgot to back up a couple of my stored excel files to a CD.
Now whenever I open them. They just come up as gibberish.
Can anyone point me in the right direction as to how to recover the information contained in these documents.
Thanks.

[Viceman]

Save copies of the files from within Excel 2007 explicitly choosing the Save
As option for Excel 97/2003 (.xls), or

Wait until you upgrade to Office 2008 on the Mac side which will use the
same formats as Office 2007.

[htvan]

Save as option for Excel 97/2003 (.xls) has done nothing.
Any other suggestions?
I have tried a few excel repair programs. But none have made any difference.
Cheers.