I have the X75 and have run it for about a year with no problems. You can buy it for $5 more at Staples ($10 higher, but $5 more rebate), and might be worth it to get a little better speed. I'm using it on Windows XP Pro with no problems, and also sharing it out to 3 other computers on my home LAN.
Understand when they say fax capability, they are talking about using the computer's internal fax with software they provide -- basically you are just scanning the document(s) then faxing them as a separate step. Multiple pages are a little more hassle since you have to scan and save each page, then batch "print" them to the fax program.
Biggest drawback: price of replacement ink cartridges and fairly short life. Staples gets $55.76 for a combo pack of color and black for the X73, with estimated 600 pages black and 275 color. The X75 uses different carts, but similar price and capacity. A person can usually find them on EBay for around $22.50 each shipped, or use remanufactured to maybe save a few buck (I have not had good luck with those). The cartridges don't last all that long -- I am probably spending $200 a year on ink with moderate home use. Also, the problem of ink waste with any printer that uses a single color cart.
Scanning capability is great, and a convenient copier for normal home use (like making copies of all those rebate documents), but not suitable for heavy copier use due to speed. Printer quality is excellent -- I have printed quite a few photos which turned out very good.
My opinion: good printer for light home use with occasional scanning, copying, faxing. It does the job for me while using up very little desk space. Don't let the ink run out where you have to go buy local retail.