I search for the internet and try to buy ASA5505-BUN-K9 or ASA5505-SEC-BUN-K9 . Are those two firewall products can meet my requirements ?

I would strongly recommend a higher tier ASA like ASA 5520/40, they are Gbps interface firewalls for 100 users.

5505 is 100Mbps intarface based, restricted features and no failover capability (well no active/active failover).

For example total traffic is only about 150Mbps via ASA 5505, 5520 gives you 450Mbps, 5540 650Mbps............. 5580 10Gbps

Other considerations are multicontext number, concurrent sessions supported, VPN traffic, expansion, IDS...etc....

See:

http://www.cisco.com/en/US/prod/collate ... 930c5.html

Actually, ASA5505 is 100Mbps intarface based.But whether it is suitable for you depends on your needs,for example,the number of interfaces, throughput, IPS throughput,and so on.
You can visit http://www.3anetwork.com/cisco-asa5505- ... _p614.html ,you can get more information.
And if 5505 is not suitable for you ,you can try this http://www.3anetwork.com/cisco-asa5520- ... _p589.html.
If you have any question,please connect me:[email protected]