If formatting is not an issue, you can simply copy and paste Chinese text from one platform to the other using most emulators, like Virtual PC and SoftWindows. This can be the least troublesome way of exchanging raw text, since the emulation software handles the conversion. This is a difficult and frustrating topic. The standard external file translation utility, MacLink Plus, is simply not designed to see double-byte text all the way through the transfer. See below for a link to Robert Smitheram's experimental solution for Mac to Windows transfers using the MacLink Plus RTF format.
Pepper is especially agile.
Microsoft has at last made Word for Mac somewhat responsive to handling Chinese text, and documents can be exchanged with those created by Word for localized Chinese versions of Windows, as well as Word for Windows with add-on Chinese system extensions. Office 2000 has the abiltiy to mix Big Five and GB characters in one document. When preparing a file with some text editors , like BBEdit, you can also save it in the PC format. This page includes an experimental code converter that converts MacLink Plus RTF documents into Unicode RTF text. Unfortunately, I found that my 74K file crashed certain PC computers.