Not really, as the MacBook (MB) uses an outdated CPU (Core 2 Duo) and a less capable integrated graphics processor (IGP) and has less RAM (and slower RAM, albeit the 2008 MB can be upgraded to 6GB RAM). The display also has less screen real estate (1280 x 800 pixel in the MB vs 1600 x 900 pixel on your Dell, if it is the 17" one).
I sold a similar 2008 MacBook last year for 500 , I guess they now go for 300 to 400 . If that is the all the money you can get for your 2011 Dell nowadays, then go for the trade, otherwise do not trade, if specs are your main concern.