The GameCube version of Summoner 2 will have:
Improved texture resolution and color in all environments
Enhanced lighting in all environments
Enhanced character textures for all lead party characters, Iari, Neru, Morbazan, Sangaril, Krobelus
Improved animations for all lead party characters
Higher animation sampling rate (animations look smoother because they play faster)
S3TC Texture Compression (allows you to compress and decompress higher quality textures in smaller memory footprint)
Higher resolution audio FX and Soundtracks (takes advantage of 16MBs audio RAM on GCN)
Hardware supported geometry compression (faster load times)
http://cube.ign.com/articles/371/371763p1.html