How do i find compatible graphics card

Hello,I want to upgrade my graphics card as mine just doesnt have the capability to handle some things i want to do. However i dont have a clue what to look for or what will even fit! Its an Acer Travelmate 240 running windows vista. Ive upgraded the RAM to 1gb but apart from that its standard. Could someone please tell me some various options (cost/performance-wise) In device manager it states that the display adaptor is 'Intel(R) 82852/82855 GM/GME Graphics Controller (Microsoft Corporation - XDDM)' (dont know if this helps!) If i need to give you more information to help please tell me where to find it as im a bit of a novice! Thanks in advance!