Homegroup not detected/DSL via switch set-up

Hi everyone,

I've been running through this forum looking for help with an issue, but I figured I should post as well since every case has its on quirks (at least in my case)

To begin, this was all begun with the simple intention of sharing a USB-wired HP 3005 printer over a wireless network. The desktop is running Win 7 Home Premium x64 is connected to a wireless router (linksys E2000) via Ethernet and said router is connected to the internet through a walljack that goes to a switch which connects the whole office and has the Verizon DSL modem plugged in to it as well. We use the wallswitch to share the DSL modem's connection with all the other jacks.

I only need to share the printer with computers that connect to the wifi network, so I've been testing it out with a wifi-connected laptop running Win 7 Home Premium. The problem is that the laptop can't locate the printer on the network even though it has no problem finding the desktop.

I then tried to do it via the homegroup feature, but that isn't helpful as neither computer recognizes each other's homegroup. The only option I get is to create another one even though there may be an existing group on the other computer.

here's a little network map. The highlighted min-pc is the laptop.

[IMG]file:///C:/Users/Min/AppData/Local/Temp/moz-screenshot.png[/IMG]

Troubleshooting performed...
1)Synchronized clocks on both computers
2)Shared printer on desktop
3)Installed HP pcl6 driver on laptop
4)Disabled McAfee firewall (only on laptop, desktop has MSE)
5)Disabled AP isolation on wifi router

These are all the steps I kept in place. I believe the issue may be coming from the desktop's connection set-up. It used to go directly through the wall jack and thus to the DSL modem, so it still has a Broadband PPPoE connection saved in it. It's saved as the default on the computer and file/printer sharing is disabled on it. I don't think it should matter has it connects to the internet via the port in the wifi, but, whenever I play with the settings it kills my internet connection.
Regarding this default PPPoE connection, it kills my internet connection via the ethernet-to-wifi router if

1)I remove it as the default or delete it
2)Activate file/printer sharing on the connection
3)Set the wifi router to PPPoE mode, this also kills the internet connection to all computers connecting via wifi.

Another side-note that might explain my issues with the homegroup, my desktop pc doesn't have an ivP6 ip, I think I read somewhere that homegroup needs it to function properly. In that respect, I tried alternatively using a work network setup via ivP4, but that still doesn't show the printer when I try to add it on the laptop with the wizard.

So, I'm pretty confused as of this point. I think I have to remove the PPPoE connection on the desktop to move forward, but that would mean having to connect the modem through the router and then the router through to the main switch for the office. I tried doing that when I first got the wifi router, but it caused some weird issues with another office on our floor that goes off the main-switch and connects it to another switch in their area. It caused loss of connectivity for some of the computers under that second switch and it killed their vonage service, so I'd rather not go through that route again.

Arghhh, any ideas o mighty wizards of the intertubes?