Hahaha! Definitely hate it.
Ok firstly lets see what has been done already.
1: You have correctly setup Workgroups on all machines I.e. MSHOME (it has to be the same name).
2: Now you need to make sure you have enabled File/Printer Sharing on all machines.
3: Once the File/Printer sharing is enabled, then you have to go to Control Panel--->Windows Firewall---->Exceptions--->Check the Check-box which states File/Printer Sharing Files. This will allow firewall to open the ports.
4: You need to make some folders on your machine/Laptop to be shared (right click on the folder --->Properties--->Sharing tab--->Check the box Share this folder (its upto you to allow people to change files within that folder, if you do then check the check box which states "Allow others to change the files". Click Ok.
5: Now open My Network on each machine to see if folders are shown.
For your weak connection issue, I think there are two ways.
1: Buy an N+ draft router and USB Key and use that router instead of your standard b/g router. This will allow it being strong signal as well as high speeds between the router and the machine.
2: You are correct about the repeater, you can buy a strong signal repeaters to place them in the between to make the signal stronger.
One of them I saw on google products from Linksys (a CISCO company) - (URL: Linksys Wireless-G Range Expander WRE54G Repeater - External
Could you tell me what sort of budget you have for a repeater? We can then look at different products are those prices.
Please let me know if any of the above worked for you