D Link DSL 2640T Wireless Speed Issue

Have an ADSL2+ connection on my D Link 2640T modem , when i use the wireless option with it right next to my laptop (XP, Dell inspiron 6000 5 yrs old) i am getting speeds around 35-40 kb/s , but when i tried the ethernet cable option i get download speeds of 150-250 kb/s.

I tried looking through the wireless settings but i dont know whats limiting my wireless speeds that low.

Would anybody be able to give me ideas on the settings that might help me improve my wireless speeds please ?

THx