The digital versions of Oblivion are completely stripped of SecuROM DRM, ship pre-patched to v1.2.0416, and feature modern OS optimizations right out of the box. The GOG version is highly recommended for modding, as it comes pre-applied with the Large Address Aware 4GB patch.
However, as one forum moderator stated:
If you're eager to experience the world of Cyrodiil without the hassle of no-CD cracks, consider purchasing Oblivion 5th Anniversary Edition through official channels. Join the thousands of gamers who have already discovered the joy of playing this iconic game without the need for cracks or workarounds. oblivion 5th anniversary edition no cd crack work