Hello,
Current Setup on existing domain:
I have a forum software script named vbulletin setup in site root (my bad did not moved it to forum while initiating few years back)

Assuming I am going to build a huge article repository on “hardware” (I want to gather as much information/guides/reviews/faqs/tutorials/new product showcase on hardware)
I am going to display general hardware related news from hardware manufacturers on site root.
I will be taking care of similar .php files (as i am on unix environment)

There will be numerous main categories ( and subcategories with company names) like:
Motherboards
- Asus
- Gigabyte
- Intel
Storage
- Seagate
- Samsung
- Intel
- IBM
Display
- LCD
---Samsung
---Philips
---Viewsonic
- CRT
---Samsung
---Philips
- Plasma
---Philips
---Viewsonic

In all there shall be more then 100 categories, sub-categories and sub-sub-categories each having more then 50 articles in same.

How should i setup?
What content management system (free or paid) shall work best? I am planning for Expression Engine but seems little difficult to make clear/precise URLs

I am looking for clear (keyword rich URLs) here:
Example:
www.mydomain.com/motherboards/
www.mydomain.com/display/LCD/Samsung/

Please help, I am looking forward from a future perspective of site, some expertise will be very helpful here before I start feeding content.

Regards,