help finding free VPN Client software (is it necessary?)

Work just picked up a Sonicwall VPN router. For VPN Client it appears I have 3 options:

1.) sonicwall client
2.) freeware VPN client
3.) built-in Windows VPN client

Can I get some recommendations on which is best? Can I just use the Windows client and everything will work fine or do I need dedicated software?

Is there a freeware VPN Client that is reputable (perhaps something along the lines of TrueCrypt's reputation with encryption)?

I'll be setting it up for IPSec so workers can use their laptop to "call" the router and establish a tunnel.