Hi Jon,
To be completely honest with you, converting the theme to something XOOPS can use is really pretty easy. There are a few things that you have to do to get it to work, but its more time consuming than anything. FIND & REPLACE IS YOUR FRIEND!!! There are a few XOOPS smarty variables that are highly important IMHO. <{$xoops_url}> and <{$xoops_imageurl}>. Now of course the easiest way to find out how a theme is built is to take the default template and edit the theme.html file. In that file you will see how it is built and what you need in the html files supplied from template monster to get it to work.
Its a job that takes simply time to convert all of the image paths to the xoops_imageurl paths. If you would like to see how I did mine, I can post some of the code here if you would like.
As far as resources for templates, there are a few sites out there that offer pre-built templates, but just do a google search to find them. I used 3d gaming templates as a search in google to find the template I am using ATM.
Template Monster is the biggest resource that I have found to date though.
Now something that you need to consider, and I will suggest this to all that do get a pre-made theme tempate, make sure you have an idea as to how your site will be layed out. By that I mean the width of the theme has a lot of effect on what blocks you will be able to use and how the navigation will be constructed. If you look deep into my site, you will notice that I eliminated both the left and right blocks on some of the modules. Why some of you might ask, well to be honest the theme wouldn't render properly with them. So that is the main reason for the navigation menu at the top right under the main image.
Also, when you are building your css file, I found that some of the styles were contained in the html files. You have to take those out of the html file and add them to the style.css file. What I did to get started was take the existing default theme and rob bits and pieces from the css file to construct the one that I am using now. You have to to get the styles that are needed by XOOPS to render some of the features properly. I just basically copied the style.css file, the block html files that are in the default folder and used them as a building block persay.
here are the contents of what you probably will need....
theme.html
theme_blockright.html
theme_blockleft.html
theme_blockcenter_l.html
theme_blockcenter_r.html
theme_blockcenter_c.html
style.css
styleMAC.css
styleNN.css
All of these files can be copied from the default theme to get started. Like I said before just edit the theme.html to see how the tables are layed out and what not. You will quickly see how and what you will need to copy and move to get it working. Most full sites from templatemonster will come with more than one index.html file. Mine came with index.html, index_1.html, index_2.html.... etc. Just open what ever one suits your taste, I chose one that had a large open area in the middle, to work off of. You need to copy the info out of the top of the default theme.html also. The info that is in the tags and add it to your index.html file.
Now once you get your theme file edited, and all of the image paths converted.
example of a background image tag
background="<{$xoops_imageurl}>images/l1.jpg"example of an image source tag
That is the easiest way to convert tags that call to images. Just do a find replace for background=images/ and replace with background="<{$xoops_imageurl}>images/
And the same goes for the img src
Just do a find replace for img src=images/ and replace with IMG SRC="<{$xoops_imageurl}>images/
Pretty easy.
Those are just a few tips that I have on converting one. As far as the css goes, experimentation is the only key to it. Find what looks good to you and roll with it.
Feel free to stop by the site any time and post. I think I am going to write a tutorial on converting a theme from a templatemonster source, it might come in handy down the road.
Laters,