I've played with Zorin and I like it. Recently installed Lubuntu on that older Inspiron 1501 and it runs slower than Zorin on the D620.
The only thing I can find that's less expensive than the 64-bit Win 7 pro is the 32-bit version of same, and it's only a few dollars less.
Apnea Board Moderator
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
The home version in 64 bit will run nicely and it gives you the headroom to up RAM capacity if you like. The 32 bit version is limited in amount of RAM. I loaded the 32 bit on an older Inspiron laptop (was running XP) and it runs fine, but I did not load Aero and a few of the other higher end elements that would have caused conflicts with the built in video.
Meanwhile I loaded the 64 bit version on my 7-year old home-built computer that was still running an e6300 chip and 4 GB RAM. I did replace the aging video card so I could handle Aero. I then replaced the chip with a P960 quad core and overclocked it a bit. Also upgraded RAM to 16 GB and stuck in a Caviar Black HD. It will run with the big dogs even though it is pushing through an aging chipset on the motherboard. Next and final upgrade to this platform is an SDD drive. I really like Win 7. It is the most robust OS that Micro$oft has ever built. Not yet sure about 8, and I'll move to 8.1 anyway, but that upgrade will probably come with a totally new build.
Just be careful with a home version, I fell into this trap and when I wanted to install some software that was commercial grade ie business related that I wanted to be able to occasionally use at home it wouldn't work because of some incompatibility. Caveat Emptor. If the price difference is minimal and you can afford it, buy the best option always.