T40 rapid battery drain while in Standby/Sleep

[t40_owner]

T40 1.5 Centrino (2373 model). I recently upgraded the OEM 40GB Hitachi hard drive with a new Seagate 5400.3 80GB drive. I did a totally clean install on the new drive, then fully patched via "Windows Update", then downloaded Thinkvantage System Update which patched various drivers including the newest version of the power management driver. BIOS has not changed since drive upgrade, and is still the most current. The battery used to drain at a very slow rate while in standby. It is now draining too rapidly in standby. For example, last night I put the computer into standy with my 9 cell battery at 78%, and this morning (exactly 8 hours later) the battery is down to 43%. Usually I'd expect maybe a 10% drain max over that duration. The other symptom I've discovered since installing this new hard drive is that it takes much longer for the computer to enter standby mode when closing the lid. Previously the computer would go into standy fairly quickly (say 10 seconds or less). Now it usually takes a good 30 seconds. This is frustrating as I know I've introduced several new variables at once (new drive, new drivers). Is it possible this could be strictly hard drive related, or is it more likely some conflict with this newer power management driver? Is it possible to find an earlier version of the power management driver and install it? Any advice is much appreciated.