I have a Dell Inspiron 1545 laptop made in 2009 with an Intel Core 2 Duo P8700 cpu (it came with a Pentium Dual Core T4200 but I upgraded that for $20 a couple of years ago. An Intel Core 2 Duo T9400 cpu with 6mb cache is now on order for $7.95), 4gb ram and a 160gb hard drive are currently installed. It will accept up to a T9700 or P9900 Intel Core 2 Duo processor, 8gb ram and a 500gb or 1TB sata hard drive. Check Ebay for some really good parts deals as a lot of these computers are being parted out and sold there. This laptop shipped with Windows Vista just as Windows 7 was coming out, so it was upgraded to Windows 7 for free in 2009. It came with 2gb of ram, but an additional 2gb of DDR2 PC2-6400 800MHz non-ECC 200-pin ram is currently only $10. Check the Dell website and make sure it has the latest bios installed. Check out YouTube for many upgrade videos. The cpu can be changed in about 15 minutes and ram added in less than 5 minutes.
I recently installed, as dual boot, Linux Mint Cinnamon 17.2, 64-bit. The old computer really flies running Linux. Give it a try. Windows 7 (upgraded to 64-bit) takes 30gb and Linux takes up about 10gb of the little 160gb drive. It has LibreOffice installed in both Windows 7 and Linux Mint (Linux Mint comes with LibreOffice and Firefox browser). I downloaded the Linux Mint ISO and created a bootable USB flash drive from the ISO using Rufus. Don't mess around with a DVD install, a USB flash drive will install Linux in about half the time.
I didn't have to add one driver in Linux. All of the Dell hardware was automatically detected and drivers installed. Wifi is working great on the original internal Dell installed Wifi card.
My wife also has a Dell Inspiron 1545 laptop made in 2010 with similar hardware upgrades that I installed. That computer is running Windows 10 x64, and really well. It upgraded without any problems.
So those little old Dell laptops have a lot of life left in them.