Sonic Team has recently released a demo version of Phantasy Star Online for PC. It's downloadable off of their website and is available in multiple languages, including English. The demo gives you access to only the forest 1 area of Ragol, and features basic combat with the HUmar class; player injury is turned off and there is no sound. Note that the demo version does not allow online play. The setup file is 13 megs in size, and you will need DirectX 8.1 installed in order to play.
The retail version of Phantasy Star Online for PC is a direct port of the Dreamcast game Phantasy Star Online Version 2. However, it features client patching much like other online RPGs released to date, allowing new things to be downloaded and added, unlike the Dreamcast version. In addition, the adjusted save system allows multiple characters to be made, rather than being restricted to one character per memory card. The PC edition goes on sale December 20th in Japan.
In order to play PSO online, you will need to register at ISAO.net for a username and password. The cost to play online is twice the cost of the Dreamcast version: 1000 Yen for 30 days (roughly $8.00) and 2000 Yen (about $16.00) for 90 days.