Is there a particular reason why you are wanting to use an old 4.x client (4.8 released January 2007) with an ASA latest release?
I have used the current 5.0.07.0440 client successfully on 64-bit Windows 7 with ASA 8.4.
Just to test I downloaded 4.8 client and note this warning page is presented:
Dear Valued Customers and Partners,
In an effort to assist our customers and partners in using Cisco's recommended VPN software releases, Cisco is archiving and deferring (i.e. removing) from Cisco's Software Center potentially vulnerable and older software releases of the Cisco Secure Desktop (CSD) and of the Cisco VPN clients (Cisco VPN client (IPsec), SSL VPN Client (SVC) and Cisco AnyConnect VPN client).
Cisco strongly recommends use of the latest VPN client and Cisco Secure Desktop software versions, as available on Cisco's Software Center, in the
Latest Releases folder for each product. Recommended software includes fixes to security vulnerabilities announced by PSIRT, incorporates the latest feature-sets, and supports best practices deployments.
As new updates are released, the most current VPN software versions will be published on Cisco's Software Center. Prior releases will be superseded and either archived or deferred from the Software Center. As an accommodation to our customers, archived releases will still be available on Cisco's Software Center in a separate All Releases folder. Deferred releases will be removed from Cisco's Software Center and can be obtained by special request through Cisco's Technical Assistance Center (TAC).
All archived and deferred software available through the Cisco Software Center or through TAC is provided by Cisco expressly on an "AS IS" basis, without warranty of any kind. Such archived or deferred software may contain known security vulnerabilities or other bugs that have been fixed in subsequent software versions.
DocumentationCode download linksGoalRequirementLimitationsSupported ISR
and UCS-E ModelSupported ISRG2 and UCS-E Blades:Supported ISR4K and
UCS-E Blades:Step by Step ConfigurationConfigure one of the connectivity
options to access the Cisco IMC from the n...
Firepower Threat Defense (NGFWv) on UCS E-series - Transparent Mode in
HA DocumentationCode download linksGoalRequirementLimitationsSupported
ISR and UCS-E ModelSupported ISRG2 and UCS-E Blades:Supported ISR4K and
UCS-E Blades:Step by Step ConfigurationCo...
Question I am currently unable to specify "crypto keyring" command when
configuring VPN connection on my cisco 2901 router. The following
licenses have been activated on my router :