Will GTA Vice City lag on my Macbook Pro?

Hi all users on gtaforums.com. I was just wondering now when Gta III, Vice city and San Andreas are released to mac by steam, will they (or just Vice city, because i want that most) then lag on my Macbook Pro from (i think) 2009, with Snow leopard, Version 10.6.8 and Processor 2.26 GHz Intel Core 2 Duo? I am not so much into specs and so on, so just say i there are any other specs that are important in this case, but here are some further specs: Model-id: Macbook Pro 5.5 - Processor speed: 2,26 GHz - Memory: 2 GB - Chipset model: NVIDIA GeForce 9400M. I am just thinking about playing singleplayer, so would my Mac could run it without lag, or at least with not that much lag? And are there a way i can degrease the lag if it does lag? And will it help if i install OS X Lion? Please help me I really want GTA on my Mac because I am a big fan of the series. And please dont comment on why I have a Macbook when i am a player. Help!