Hi,
F&D speakers that you have are powered/amplified speaker system. These do not required to be connected to an amplifier to work, rather can be connected directly to source (PC/Music Player, etc...).
I think your budget to too low for multichannel (5.1 or more) AV receiver.
If you are thinking of upgrading to home theatre system then you may have to start looking at Yamaha/Onkyo/etc. HTiB starting @20K+