Network Architecture Question

Greetings Everyone,

I have a question about the architecture in our home network.

Our current network setup is like this:

(= and || are wired connections, ~~~ is a wireless connection and _ is used for visual spacing)

Where:
Switch I is a 8 port 1 Gbps Switch(Netgear GS608)
Switch II is a 5 port 1 Gbps Switch(Netgear GS105)
Switch III is a 8 port 100 Mbps Switch(Netgear FS108)
Router/Modem and Wireless are both 100 Mbps

But here is de problem, I always stream media from Computer 4 to my PS3, but since I added Switch II en switched Switch III en I, I have been experiencing lags(or stutters) in the stream(I can't see the stream, but in the anime(movies) I noticed extreme stuttering). So when Computer 4 was connected to Switch III, the streaming went perfect unless the data stream was above the 100 Mbps. Now since I connected Computer 4 to Switch II the trouble started, and the anime(movies) seemed to lag(or stutter). But I do not understand why, because it is not like Switch II is slower than Switch III.

So I came up with a new setup to fix the streaming and increase the stream capacity:

where:
Switch IV is a 8 port 1 Gbps Switch(FS108)

Now my question is, will this solve the problem? And increase the connection speed between Computer 4 en my PS3 to 1 Gbps?(PS3 has 1 Gbps support)

Hope someone can help me...thank you in advance...

(to summarise: Why did it start to lag when I increased the Switch speed to 1Gbps from 100 Mbps?(is it because the router that connects the two is 100 Mbps) and does the new setup fix the problem and increase the connection speed to 1Gbps?)

p.s. in the new setup I switched Switch I and IV around, because Switch I is hidden in the new setup and Switch IV is located in my room(in the new setup) and I personally hate the white colour of Switch 108.