Thats what Excel is good at why they want you to re-invent the wheel ? that's dumb. Distribute an excell spreadsheet the end user fills it in, emails it or saves it some server share, import it into the database. ASP is for web applications it ain't a spreadshhet that's what spreadsheets are for.
You could do it, but you need a hell of a lot of text boxes, and you may have problems with the maximum amount of data allowed in an HTML POST.
I recon if you have to use asp you need one 'records' worth of text boxes, ie one text box for each column and then a HTML table underneath. The user fills out each box for one record and hit a submit button then you can post that to the server stuff it in the DB, concat out HTML table back to the client ready for next client.
you can lock the workbook, sheet(s), columns or cells.
In the properties of an individual cell for example there is a checkbox in one of the tabs (the last one I think) that specifies whether the cell will be locked/unlocked when you lock the whole sheet. This way you can lock most of the sheet and users will only be able to modify the small number of cells that you want them to . The rest you can control programatically with VBA code which can also be password protected.
I havn't used Excel much for a while so I'm a bit rusty. But here's some good stuff about it: