Cascading Combo Boxes in User Form

This is my first Post:
Excel 2007

I am attaching the test work book
I created a pricing tool using multiple worksheets (72)
There are about 5 manufacturers and mutiple models
I need to add the full row (starting with qty)

Each model has multiple accesories
Some accesories are required
Some accesories cannot be added togethor

I created a form that works using only formulas - but would rather use userboxes.

Combo box 1 mfg - point to list on first sheet
Combo box 2 point to list on different sheet (dependant on choice 1)
combo 3 point to the model's sheet

Is there a good tutorial that assumes no beginning VBA skills

any ideas - I saw a post that uses a combo box then a list - what do you do is the ranges are on different sheets?
i.e. choose mfg1 (ComboBox1) - than use range from mfg1! (ComboBox2) or choose mfg2 - then use range from mfg2!