Oracle have transparent gateway software to link other db's like db2, sybase etc. Below is the certification info from metalink for W2K, I haven't user the sybase version but I have used the same software to share information between DB2 and Oracle and it works a treat.
Certify - Additional Info Oracle Transparent Gateway for SYBASE Version 9.0.1 On Microsoft Windows 2000
Operating System: Microsoft Windows 2000 Version 2000
Oracle Transparent Gateway for SYBASE Version 9.0.1
Oracle Server - Enterprise Edition V8 Version 8.1.7 (8i)
Product Version Note:
None available for this product.
Oracle Transparent Gateway for SYBASE v9.0.1 is certified against Oracle 8.1.7 (8i) and Sybase version 11.9.2 and 12.0.
NOTE: If the Sybase Server is not on the same machine as the 9.0.1 Gateway, then Sybase Open Client Library certified for the Sybase Server is required.