Hello,
That depends on how small is the company, based on ASAs I will recommend the ASA 5505 ( Built for SOHO:Small Officess and Home offices) or the ASA 5510 (Built for small offices to medium officess)
You can take a look at this link in order to see all the features that this ASAS will provide you (Throughput,modules supported,etc)
http://www.cisco.com/en/US/prod/collateral/vpndevc/ps6032/ps6094/ps6120/product_data_sheet0900aecd802930c5.html
Regards,
Julio
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Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC