Refurbished does not mean there Used.
Refurbished/Recertified systems have some new parts, if its private retail. So, the battery won't be a huge issue. The manufacturer, tests every single dang part thoroughly, than sends the good LapTops to Retailers across the country.
Used can mean.
Tested without installing new parts, install very very few parts with and/or without testing. Or not tested at all. In many used cases, only the HardDrive may have been tested thoroughly. Other parts may have been just quick tested. All depends on where the used LapTop came from.
They use lots of testing supplies, plus testing software and probably use http://dban.org to securely wipe the drives.
Sometimes refurbished computers run better than a new system. Pentium M or higher and 1.8ghz or higher will be the best choice. Many older systems are not Windows7 ready (don't bother with Vista). So, make sure it says WinVista or Win7 Compatible. Windows 7 and XP will be compatible on a Vista or 7 System.
Windows End Of Life:
Seven Pro supported by Microsoft til, 2020 (XP Mode)
XP supported by Microsoft til, 2014
Seven Premium supported by Microsoft til, 2015
Seven Ultimate supported by Microsoft til, 2015 (XP Mode)
Windows System Requirements:
XP
http://www.microsoft.com/windowsxp/sysreqs/pro.mspx
Seven
http://windows.microsoft.com/systemrequirements
Sourced From: Microsoft