I have had mixed success importing PDF fles into Omega 2.1 on
Windows 98SE. Mostly successful. You are best off looking at the file in Adobe Reader prior to importing in Omega so you know what you're looking for and, in the case of multi-page PDF's, which page it is on.
I more often open the PDF in Adobe Illustrator 10, which does run on Win 98, and save what I need from there. Coreldraw also opens PDF files.
The thing to bear in mind is that Omega will have the same limitations in reading an Omega unsupported effect in a PDF file that it has in reading it in an EPS or AI file. If someone uses, for example, a gradient mesh in Illustrator and saves it as a PDF, Omega will struggle with it. But the same will be true if it is saved as an EPS.