My recommendation would depend on the amount of RAM. If you have at least 1 GB RAM I would recommend the MATE version of Linux Mint Maya. Linux Mint Maya is based on ubuntu 12.04 and is thus a LTS version. The MATE version is the Gnome 2 fork. So as an Ubuntu 10.04 user everything will be very familiar.
If you have 512 MB RAM I would recommend Xubuntu 12.04 for you. The new XFCE 4.8 interface has nearly all the functionality of Gnome 2, is less of a resource hog and looks awesome. Xubtuntu 12.04 is an LTS version, but is only supported for 3 years. It hasn't got Libreoffice installed, but it is available in the software centre.
I don't know for your particular printer, but as of the 12.04 versions you would not need to install HPLIP anymore. The printers, which before required the installation of HPLIP are supported out of the box.
There is also Lubuntu, it is very light, but darn ugly. I would not recommended because your processor should be quite capable for xubuntu or linux mint.
My configurations:
Xubuntu 12.04 on an eee pc 1005 HA (main)
Ubuntu 12.04 on a Dell dimension 4800 ; PIV 2.66 Mhz, 1.5 GBRAM
Xubuntu 10.04 on hand build AMD Athlon 1500+ 1.33 Mhz, 0.75 GB RAM