EagleView is probably a bad choice for viewing EST assemblies. Consed might be better. You also might want to test clview (from the same TGICL site) for viewing your assembled clusters.
In general, I'd recommend MIRA3 (
http://chevreux.org/projects_mira.html) for assembly of sanger/454 based EST datasets. It works fine (at least in my hands) and lets you the choice using ACE based viewers, Staden's gap4/gap5 or even nedit ;-)
hth,
Sven