Try PocketDivXEncoder. It's free, and video quality is excellent if you use the XviD codec. It also supports B-frames, which is nice if you have the CPU for it - which the 4700 certainly does. I encode smaller than VGA resolutions, such as 512 width, because the resize filters make the difference in video quality negligible. Especially when you factor in movie size and bitrate, which must increase assuming larger resolution and similar quality.
Of course you should do a bunch of test clips and find which settings you prefer. There's a rather nice program called AutoGK
http://forum.doom9.org/showthread.php?s=&threadid=64266 and it does almost everything for you. If you're new to ripping/encoding, see doom9.net for tutorials (and DON'T use QPEL or GMC!! they recommend these, but you cannot play them with BetaPlayer)