Seems to be several, NCP Secure Entry Client touts Windows 7 compatibility for instance.
As far as the built-in VPN client it supports several standards including IPsec since like NT4 or atleast Windows 2000 days but from what I know some features are missing which makes it not always compatible - but it's worth a shot.
Windows and Windows domains uses IPSec natively to secure traffic so it's not like it's not there, just that the client-side part might not be as flexible as an enthusiast user might want - normally it'll be configured by administrators with ipsec policies internally on a company network...