One of the main uses we get out of our Adobe Illustrator application is in opening almost anything that comes our way with an EPS extension. Once open we are able to determine its suitability for production and other criteria. Several applications we have used are not capable of opening their own EPS exports ... including FlexiSign and CorelDRAW X3. If the file is a CS3 file then I don't think Corel X3 will open it.
With Corel try manually selecting the import filter from the drop down list. I get the best results with the filter named AI - Adobe Illustrator. You can also try the PS, EPS, PRN-PostScript filter as previously mentioned. If that doesn't work, find someone with a copy of Illustrator and have them save it back to a version 8 for you. Then Corel X3 will open it without difficulty.