Thomas Greene of The Register has a fairly comprehensive review of Vista and IE7 user security measures. The verdict is: better but not adequate, and mostly an attempt to shift blame onto the user when things go wrong. From the review: "[Vista is] a slightly more secure version than XP SP2. There are good features, and there are good ideas, but they've been implemented badly. The old problems never go away: too many networking services enabled by default; too many owners running their boxes as admins and downloading every bit of malware they can get their hands on."
panic: can't find /