First off, it might not be your ram but your vid card (drivers?)
Second, about the quests
Venom stone (lv 15 or 20 req, not sure)
Bring: 5 Bat Wing, 5 Nail, 3 Tooth, 3 Mushroom , 3 Fur
To: Lavender town. NPC: Colin.
The Leaf stone is fairly simple. Lv 30 req.
Bring: 135 leaves
To: Celadon city. NPC: Susy
rep plz ? ;]
edit-
Susy gives you a SECOND quest aswell just so you know
Which will require you to bring her 30 nails for abouts 650$ or so..
Where do you get the mushroom and the fur?