Fiber Optic Scope Source

I've got the red, yellow, and white rca jacks plugged into my standard definition tv, so my component plugs are free.
If I plug this
(http://www.amazon.com/exec/obidos/tg/detail/-/B000E9U9G2/ref=ord_cart_shr?%5Fencoding=UTF8&v=glance)
into my component plugs and this:
(http://www.amazon.com/exec/obidos/tg/detail/-/B000QEDE76/ref=ord_cart_shr?%5Fencoding=UTF8&v=glance)
into the coupler and the vga plugs, will I be able to play xbox 360 in high definition on that monitor?

My plan is to us the switch on the plug (that goes into the 360) and the option in the menu (on my monitor) to switch between the tv and my monitor.

Will this work? and with a 25 foot cable, will I get a lot of interference?

I hope you can help me.

I have my 360 connected to my LCD monitor using HDMI, Ive been using the in built speakers on the Monitor but it as started to annoy my mum a little, especially at night, so I wanted to use my pc headset but my monitor has no port to plug them into :

So I was wondering if I use this cable that came with the 360 http://www.erenumerique.fr/images/je...ble_avance.jpg

then connect the white and red audio to this http://www.amazon.co.uk/Triple-Phono-Female-Connector-Coupler/dp/B001D8E51I/ref=pd_sxp_grid_pt_2_2

then connect this to that http://www.amazon.co.uk/Cables-80134-Value-3-5mm-Stereo/dp/B0020MLAFA/ref=pd_sim_sbs_ce_4

and then finally plug my headset into the the 3.5mm port, would that get sound to my headset?

Sorry, I dont know much about this stuff.

(Also I will still be using HDMI for the Video)
(I had to break the plastic cover off the other 360 cable to get it to fit in alongside the HDMI Cable xD )

Thanks..