Question : Problem: What's the differences between the Cisco 2948 Series switch and the Cisco 3548?

I'm using it to hook up dedicated servers. They both runs for about the same amount on Ebay. So, what is the differences between them and which one I should get?

All I need is the ability to have VLANs, and QoS capping. Some filtering against DDos would be bonus. thanks in advance.

Answer : Problem: What's the differences between the Cisco 2948 Series switch and the Cisco 3548?

If they are both XL models, the 3548-XL is the updated version and the 2900-XL, go with the 3548XL
XL switches run on IOS, where non-XL 2900 (i.e. 2948G) run on CatOS

If the 2948 is the "G" version, then you might have more capabilities than the 3548-XL.

They are both Layer 2 switches with very little QoS capabilities, and no DDoS features, but they do all support VLAN's.

http://www.cisco.com/en/US/products/hw/switches/ps606/ps624/index.html

The 3548-XL has an announced end-of-life:
http://www.cisco.com/en/US/products/hw/switches/ps637/index.html