Configuring preferences and options in Outlook.com
These aren't "ads" as such. There's a grey column down the right hand side of the inbox with 6 or so grey boxes, one on top of the other in it. The boxes contain things such as " Take your appointments with you. Sync calendar on all devices. Try it now." and "Add networks such as LinkedIn, Twitter and Facebook to your inbox. Start here." I have not seen an actual ad from a third party company since I upgraded to Outlook.com, but I do find this column a complete waste of space and want to get rid of it. For me it serves absolutely no purpose.
I'll post a screen shot as suggested.