monitor 60's on computer 5.1 system

jsbarbour03

I just recently purchased two monitor 60s and i do not have a home-theater reciever (yet, my next check is going towards a SONY 7.1 reciever STR-D1000) except my 5.1 speaker setup for my computer. Its a Z-5500 5.1 surround sound system. ( http://www.logitech.com/index.cfm/speakers_audio/home_pc_speakers/devices/224&cl=us,en ) I was wodering if i replace my front two speakers with the M60's, will it hurt or damage the speaker or the amp on the computer receiver? Im new to the whole audio thing so any input would be great. Im in the process of making a 7.1 surround sound and i love the polk audio monitor series. Down the road i wante to get a pair of the Monitor 40's (for the rear) and a CS2 for the center. Any input on a good 5.1 or 7.1 reciever in the $400 range?? Thanks!!

jsbarbour03

...i forgot to mention the computer surround sound is 505 watts