which one is better sd or ide

[shwoaps]

Well, it really depends.
First thing, are you doing this mod yourself? SD mod is wayyyyy easier to do for inexperienced person, and for experienced too.
And if done properly, with good 8gb(this is optimal size for speed) 10class sandisc SD, formated with 64kb cluster, you really can play many games enjoyably. Video will shutter but, oh well.
It's easy to remove, easy to manage saves, it's really useful for me, even thought i have ide hdd mod.

My suggestion, if you are doing mod by yourself, do sd mod, then hdd. If you asking/paying someone else to do it, get hdd mod.