ACM 5.1 xClient Requirement is detailed in below document (Page 62)
Notes from above document that you must consider.
* Internet Explorer 8 compatibility view should not be configured for IBM ECM Widgets (WDGT) websites. Compatibility mode exists for support of older web sites.
*IBM Case Manager browser screen resolution should be at least 1280×1024.
*Minimum of 3GB or more recommended for Client system running Browser to access IBM Case Manager.
* The following are not supported for Firefox 3.x on Novell SuSE 10. Firefox 3.x requires additional libraries be compiled and installed onto SUSE 10, before Firefox will run. The Firefox requirements are identified at http://www.mozilla.com/en-US/firefox/system-requirements.html.
Here is the setting for IE 8 without Compatibility mode.
Tools\Compatibility View Settings