I had the same problem with an old AGFA Snapscan 1212 USB model. AGFA dropped out of the scanner market and so there's no hope of updated drivers. I note that whilst Mustek are still in business the drivers for your scanner stop at XP so that's not encouraging.
The software solution - there's a fairly cheap program "VueScan"
http://www.hamrick.com/ which uses its own internal drivers and supports a huge number of current and "legacy" scanners. I'd expect it to cope with your Mustek, it works with my AGFA. However you don't get the same level of integration with other products that you are used to because the scanner remains invisible to Windows 7; there isn't an option in (say) Word to import a scanned image; you have to scan and save the image using VueScan and then import the image as a file.
As it happens I have ended up with a moderately old HP Scanner, which works using the Windows 7 generic drivers, which are good enough for simple operations. I fixed an older Canon All-In-One (MP310) and that was more use to the sister-in-law (for stand-alone copying) so we swapped devices.
Despite the VueScan software working well "stand alone" I found the lack of integration with other packages very annoying. I'd almost certainly have bought a new scanner (as buying an All-in-one whilst my printer works fine is just compounding the felony).
Prior to the Canon I'd not met an All-in-one before whilst having the ability to play around a bit. I thought the scanner on the Canon was better than my AGFA, as well as being twice as fast. This is interesting, the budget Canon scanner engine does not get stunning reviews wheras in it's day my AGFA was up with the best at the budget end of the market.
Therefore I'd say it is quite possible that even a budget scanner or all-in-one could be a better scanner than your Mustek, not because the Mustek is bad but because things tend to improve as time passes.
Hope this helps
John