Greetings!
I want to convert my Joomla 1.5 business site into a Joomla 1.7 site using K2 for the articles. I need to import my categories and articles.

Can you recommend a series of steps for me? I'm willing to create a new site and import data until I'm ready to replace the old site.

thanks,
Hope
Santa Fe Web Design

I am also looking for the same advice [1.5.24 to 1.7.2 -- I have purchased SP Upgrade to perform the migration].
I have a 1.7.2 installation that is serving as a test site, where I installed K2 2.5.1, and attempted to import articles/items and I received this error:
"Fatal error: Class 'JSimpleXML' not found in /heXYZes/boXYZeb/weXYZ4/bXYZ7/sXYZnc/public_html/mXYZ172a/administrator/components/com_k2/models/items.php on line 716"

Clicking 'Parameters' [no icon visible BTW] opens a pop-up with this error:
"Fatal error: Call to a member function loadByOption() on a non-object in /heXYZes/boXYZeb/wXYZ4/bXYZ7/sXYZc/public_html/mXYZ172a/administrator/components/com_k2/models/settings.php on line 38"

On the Items tab, I have this error:
"Warning: Invalid argument supplied for foreach() in /heXYZes/boXYZeb/weXYZ34/bXYZ7/slXYZsdanc/public_html/mplXYZ172a/administrator/components/com_k2/views/items/tmpl/default.php on line 112"

On the Users tab, I have this error:
"Warning: Invalid argument supplied for foreach() in /heXYZes/boXYZeb/weXYZ4/bXYZ7/slXYZsdanc/public_html/mpXYZj172a/administrator/components/com_k2/models/users.php on line 222"

The three (3) K2 plug-in's are enabled: system, search, users

I will continue to search the Forum in case this was already addressed (didn't find it in a search).

Also, is there a calendar within K2, or is that a 3rd party extension (displayed in demo)? I am currently using JEvents but willing to switch if one is incorporated in K2 already.

My System Info:
Web Server Apache/2
PHP version 5.2.17
MySQL version 5.0.91-log
GD image library bundled (2.0.34 compatible)
Multibyte string support Enabled
Upload limit 8M
Memory limit 64M
Open remote files (allow url fopen) Yes

Update... After a few minutes, my errors described above seem to have resolved :) and I was able to import articles/items, categories and users.
I am still wondering about the Calendar. I see something about the module 'K2 Tools' but not sure how to add/import events/items from previous calendar (JEvents). Can I import via iCal? if so, how/where? They are not Joomla articles. If you can direct me to a link/page describing configuration of the calendar I would appreciate it... in the meantime, I am still searching the forum...
Thank you!