like you said lite has only 2 memslots raid has 4
lite has 2 ide channels (upto 4 devices)udma 33/66 speed
you can put udma100 device in these channels but 66 is the max transfer rate
kg7 raid has 4 ide channels 2 as per lite + 2 udma 33/66/100 +raid (upto 8 devices)
the 2 extra channels will transfer upto 100max mb/s
preformance should be the same (if your not using raid) as hds rarely transfer faster than 66mb/s anyway!!