mac book pro update

Hi everyone.
I have just bought a macbook pro 2010 from ebay. The guy did not have any discs and said you just update online. The mac is in his name, although I have his password. Itunes is missing.
I guess I need to reset machine to my username and password and update applications to uplaod iphoto.
Can I do this on line, or should I have discs?
Thanks for your info, I am new to macs.
Mark

For your own safety and security, I ***strongly*** recommend that you RUN out and by a copy of Snow Leopard (if you're not already running it). If you are already running SL, upgrade to Lion, back up your own stuff, then use the recovery partition to ERASE the rest of your hard drive and do a CLEAN INSTALL of Lion, and then of course restore your stuff.

Until you do this, that Mac isn't really yours and could easily be being used to spy on you. Don't take the risk.

Hi thanks for your thoughts.
I dont have any stuff on it, iv only had it two days. It is set to the previous owners details, but he had no discs and said i didnt need them. there is no iphoto as an application. Do i need discs, (I have a horrible feeling I do) or can i update the os and applications on line. It has SL on it.
Thanks
Mark

Please follow the good advice that chas_m gave you. You can not download Snow Leopard from Apple, you must buy the DVD. At $29.99 it's a bargain and you'll then be able to update on line to the latest version. You need to be running Snow Leopard 10.6.6 before you can purchase Lion on line.

The iLife applications (iPhoto, iWeb, iMovie, etc.) are not included on the Snow Leopard DVD or Lion download. You will have to purchase them separately.

Thanks both for the advice.
Ill do as you suggest.
Mark