It depends, do you have much data and stuff stored on the extended partition?
Do you still want two partitions or just one big one?
You can download a free partition program called: Partition Wizard and it will take care of resizing the partitions and not lose any data either.
Free Partition Software - Partition Wizard Home Edition
Partition Wizard Home Edition is a free partition manager software designed by MT Solution Ltd. Our partition manager supports 32/64 bit Windows Operating System including Windows XP, Vista and Windows 7.
Home users can perform complicated partition operations by using this powerful yet free partition manager to manage their hard disk.