I found a Lenovo website http://www.lenovoquickpick.com/usa/system/thinkpad
and I checked Hitachi and WD too and have not found a trace of 15K 2.5" drives not to even mention a 450GB one.
Check http://shoplenovo.i2.com/SEUILibrary/controller/e/
I suspect the first two is simply ten times more and this is a 3.5" disk and that database error is why the quickpick site cooked up this rather curious match. Still, I would love to know the truth did someone hide a SAS controller in the T420s? 
@chx @s1148625 @hecke @mitchsw @gdi2k
Single Thread and Multi Thread Performance Comparison of the Lenovo T410s, T420s and recent Sandy Bridge Processors
1. Introduction and Methods
The single thread and multiple thread performance of several commercially available processors has been compared to the soon to be released Lenovo T420s. Eight systems are considered: the Lenovo T410s, the Lenovo T420s, the entire line of recently released 13” and 15” MacBook Pros, and a high-performance desktop system used for comparison purposes (AlienWare Aurora-R3).
For single thread performance the time to calculate pi to 32 million digits was used. For multiple thread performance the time to complete wPrime 1024 was used. Data was gathered from as many seemingly reliable sources as possible including notebookcheck, anandtech, and tomshardware. Outliers were removed from the sample. The author used his best judgment to get an accurate picture of the individual performances of the chips. Most of the data points are based on more than 5 separate benchmarks, due to limitations of available data some data points may be based on as few as 2 or even 1 benchmark thus the results should be viewed as approximate but telling of general threads. Results displayed in figures 1 and 2 are use the relative percentage difference equation (RPD) (see Wikipedia) to calculate the percentage difference in performance.
2. Results and Discussion
2.1 Single Thread Performance
As shown in figure 1 the single thread performance of the new Lenovo T420s is a dramatic improvement over the previous generation T410s (The Lenovo T410s is 22.5% slower). The system also beats the both the 13 inch and 15 inch entry level MacBook Pros.
For single thread performance the mobile Sandy Bridge quad-core processors do not provide a significant improvement over the 2540M in the Lenovo T420s. Most applications are single thread dependent. Having an expensive quad-core i7 will not provide much improvement in real world performance. The performance of the 2620M is lower than expected, in reality it is probably faster than shown here. The low value is probably due to experimental error with benchmarking process.
Of note the older 2010 Intel Gulftown 980 Extreme Edition (not shown) gets single thread performance on par with the 2540M (it is 1% faster). The T420s will be very fast indeed.
2.2 Multiple Thread Performance
Multi-thread performance is shown in figure 2. The entry level MacBook Pro 13 inch is significantly handicapped compared to rest due to its low 2.3GHz base speed and only 2 available cores. The T420s and T410s essentially have the same multiple thread performance. The Sandy Bridge quad-core offerings do give a large increase in multi-thread performance, with all higher end models (including the top-of-line desktop 2600K) seeing a boost of about 54% over the 2540M.
For multiple thread performance the mobile Sandy Bridge quad-core processors show a significant performance increase over the dual-core processors. Having strong multi-threaded performance in a laptop would generally be less of priority as most day-to-applications do not make use of multi-threaded performance and the dual-cores already get good multiple-thread performance. Heavy multi-threaded applications (very large simulations, computationally expensive models) are typically handed by desktops and servers anyway. It is interesting that the 2.0GHz 15 inch MacBook Pro actually outperforms the 2.2GHz model in multi-threaded applications.
Of note, the older 2010 Intel Gulftown 980 Extreme Edition (not shown) would see a performance increase of more than 100% over the 2540M. For heavy multithreaded tasks using the older Gulftown or even the older Xeons on desktops would see better multi-thread performance than Sandy Bridge offerings, at the cost of lost single thread performance compared to the 2600K.
3. Conclusion
Quad-core Sandy-Bridge processors provides almost no improvement in day-to-day performance gains over the i5-2540M processor equipped in the Lenovo T420s, as measured by the single thread performance. Quad-core Sandy-Bridge processors do provide significant increases in multi-threaded performance but at significantly higher cost:
The 2540M processor is a very good processor. The more expensive alternatives do not provide any gain in single thread performance, while costing significantly more and likely producing more heat and using more energy.
