This is a common complaint with continuous forms in Access97. In short you cannot highlight a single text box or a even all the text boxes in a row. If you try to conditionally format a field then all the text boxes in that column will adopt that format because in fact you only have one textbox in each column. Access just clones themn in each row.
I understand that Access2K allows conditional formatting which I guess would solve the problem. As for formatting in Datasheet view I don't think its possible to do much formatting other than globally set the row height, column width, background colour and foreground colour.
The only way to control the appearance of individual fields in the seklected row is to create a form with a grid of unbound textboxes and fill them using a Dlookup function with an offset for the second and subsequent rows. Complicated but it does work.
Rod