“The Web Platform Installer (Web PI) is a simple tool that installs Microsoft’s entire Web Platform, including IIS7, Visual Web Developer 2008 Express Edition, SQL Server 2008 Express Edition and the .NET Framework. Using the Web Platform Installer’s user interface, you can choose to install either specific products or the entire Microsoft Web Platform onto your computer. The Web PI also helps keep your products up to date by always offering the latest additions to the Web Platform.”

The Web PI certainly looks promising as a quick ramp-up when setting up a development environment (or even a one-off server environment).

        private bool DoesUserHavePermssionsToWeb(ref SPUser user, ref SPWeb web)
        {
            bool hasPermission = false;

            SPBasePermissions perms = this.GetPermissionsForUser(ref user, ref web);
            if (perms.ToString().Contains(SPBasePermissions.Open.ToString())
                    || perms.ToString().Contains(SPBasePermissions.FullMask.ToString()))
                hasPermission = true;
            if (!hasPermission)
            {
                // Check the users groups - this is for indirect membership;
                foreach (string groupLoginName in this.GetCurrentUserADGroups())
                {
                    try
                    {
                        SPUser groupUser = web.SiteUsers[groupLoginName];

                        perms = this.GetPermissionsForUser(ref groupUser, ref web);
                        if (perms.ToString().Contains(SPBasePermissions.Open.ToString())
                            || perms.ToString().Contains(SPBasePermissions.FullMask.ToString()))
                        {
                            hasPermission = true;
                            break;
                        }
                    }
                    catch { }
                }
            }

            return hasPermission;
        }

        private SPBasePermissions GetPermissionsForUser(ref SPUser user, ref SPWeb web)
        {
            SPBasePermissions perms = SPBasePermissions.EmptyMask;

            try
            {
                SPUserToken userToken = user.UserToken;
                System.Reflection.MethodInfo getPermissions = typeof(Microsoft.SharePoint.Utilities.SPUtility).GetMethod("GetPermissions",
                    System.Reflection.BindingFlags.NonPublic |
                    System.Reflection.BindingFlags.Public |
                    System.Reflection.BindingFlags.Instance |
                    System.Reflection.BindingFlags.InvokeMethod |
                    System.Reflection.BindingFlags.Static);

                perms = (SPBasePermissions)getPermissions.Invoke(null, new object[] { userToken, web });
            }
            catch { }

            return perms;
        }

        private System.Collections.ArrayList GetCurrentUserADGroups()
        {
			// Get the current groups for the logged in user;
            System.Collections.ArrayList groups = new System.Collections.ArrayList();
            foreach (System.Security.Principal.IdentityReference group in System.Web.HttpContext.Current.Request.LogonUserIdentity.Groups)
            {
                groups.Add(group.Translate(typeof (System.Security.Principal.NTAccount)).ToString());
            }
            return groups;
        }

Note that in the above method is checking for SPBasePermissions of Open and FullMask.

The supporting methods are also included. After checking the permissions on the web object for the current logged in user, if not permissions have been granted we continue to check each Active Directory group that the current user is a member of.