treehugger88 on "Help with Validation"

Hello,

I am wondering if someone could help me with a validation problem I am having with my blog:

http://validator.w3.org/check?uri=http%3A%2F%2Fpersonalcomputersos.wordpress.com%2F&charset=%28detect+automatically%29&doctype=Inline&group=0&user-agent=W3C_Validator%2F1.1

Line 33, Column 175: there is no attribute "sizes"

I've already fixed 30 or so errors, but I am stumped by this one. Could someone explain to me how I can fix this error so my blog can be in correct XHMTL 1.0 Transitional?

Thanks.