What UI design makes sense when the userbase is obsessed with spreadsheets

In the first iteration of the software I am working on, we wrote tons of js to simulate an excel spreadsheet like experience. Now the users are n开发者_开发百科ot happy with the amount of scrolling they have to do. Their favorite UI is excel spreadsheet. I am wondering what kind of UI would provide a win win situation for the dev team and easy to grasp for the users. Userbase is people who do number crunching day in and day out. Ajaxy UI did not fly well with them initially. App is supposed to handle large amount of tabular data.

Any suggestions would be welcome.

EDIT: The data is provided via different services that the user analyzes, provides comments, make adjustments and calculations before the data is persisted in application specific db.

I use this (heavily modified though).

Besides, there are a lot of customisable options.

http://www.trirand.com/blog/jqgrid/jqgrid.html

Datagrid library (http://dhtmlx.com/docs/products/dhtmlxGrid/index.shtml) is pretty solid, provides all of the functionality you're after. And the best part - you don't have to reinvent the wheel.

My advice is to use Adobe Flex for your client-side UI. Some high-level advantages of flex:

• Browser compatibility: any browser with a flash player will run the site (currently over 90% I believe). No need to fudge with html/css.
• Data binding: the flex framework's strongest suit is dynamic scalable data binding. Also, their data grids are the strongest I've encountered, without sorting, rearranging, resizing, pagination, etc... right out of the box.
• Server-side technology: Flex can couple with any server-side technology for back-end operations (Java, PHP, RESTful web services, and Coldfusion to name a few)
• Open source: flex is open source (however, buying the eclipse-based Flash Builder is usually a good idea)
• Customization: every flex component is completely customizable and skinnable. Nice for business apps that do not want to simply look the same as everyone else.
• Desktop: Using Adobe AIR Desktop Environment users can interact with the OS.