I would get a 2010 book since there are not that many changes between 2007 and 2010.
What's new in Excel 2010?
(From John Walkenbach's 2010 Excel Bible, pg 4-5)
When a new version of Microsoft Office is released, sometimes Excel gets lots of new features.
And sometimes it gets very few new features. In the case of Office 2010, Excel got very few new features.
Here's a quick summary of what's new in excel 2010, relative to Excel 2007:
64-bit version:
If your hardware (and Windows version) supports it, you can install the 64-bit version, which lets you create larger workbooks.
Most people do not require the 64-bit version and using it might cause some add-ins to not function.
Sparkline charts:
Create small in-cell charts to summarize a range of data graphically.
Slicers:
A new way to filter and display data in pivot tables, by clicking buttons.
New Pivot table formatting options:
You have more control over the appearance of pivot table reports.
Office button changes:
The big round Office button in Excel 2007 has been replaced by a File button/tab, displayed to the left of the tabs.
Clicking it displays a screen that lets you perform various operations on your workbook.
This view essentially replaces the traditional File and Print menus---plus quite a bit more.
Conditional formatting enhancements:
Data bar conditional formatting can display in a solid color, and the bars provide a more accurate display.
Function enhancements:
Some Excel worksheet financial and statistical functiosn have been improved in terms of numerical accuracy.
Image editing enhancments:
You have much more control over graphic images inserted into a workbook,
including the ability to remove nonessential parts from the baground of an image.
Screen capture tool:
You can easily capture a window from a different program and then insert the image on a worksheet.
Paste preview:
When you copy a range, the Paste command displays various options with a live preview so you can see how the paste operation will look.
Ribbon customization:
You can customize the Ribbon by adding new tabs and groups.
Equation editor:
Create and display (noncalculating) mathematical equations and embed them on a worksheet.
Faster:
Microsoft made some improvements to the calculation engine, and files load a bit faster.
New security features:
Workbooks downloaded from the Internet or from e-mail attachments are opened in Protected View mode.
Workbooks can be designated as "trusted," and don't need to reside in special trusted folders.
Solver:
Excel 2010 includes a new version of the Solver add-in, which is useful for solving some complex problems.
Enhancements to VBA:
Operations that used to require old XLM macros can now be performed directly using VBA macro commands.
In addition, macro recording now works for operations such as chart shape formatting.