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Q: I want to buy a USB drive. While looking around I found many different brands and large price variations. Are some better than others?

A: Despite a large variation in price, there can be some difference in performance, so my first and most important advice is to shop around. These devices can be bought in department stores, camera shops, computer shops and swap meets and prices are falling. I have seen more than 150 per cent variation in price between virtually identical units.

If you use these devices only occasionally, speed may not be a critical factor. Most manufacturers claim more than 100,000 read / write cycles, even in a harsh environment, and most claim a data retention period of more than 10 years. I have performed some timing tests on several different brands and there was less than 50 per cent difference between the fastest and the slowest in copying large files. Transfer rates in the order to 10 Mbps are possible with some units..

However, when copying many small files, the transfer rate changed dramatically for most devices. When copying my 315 favourites, which totalled 48 KB, a typical time was about 90 seconds. Deleting these files took about 30 seconds. I contacted two USB ram drive manufacturers for an explanation but did not receive an answer. The best way to overcome this problem with many small files is to use WinZip or RAR to compress them and write just one file, reducing the time taken with my favourites to less than three seconds.

However, a relatively obscure USB drive called My Flash was the cheapest and fastest in copying large files, copying my favourites in only 15 seconds. I paid $40 for a 256 MB drive in late March at a swap meet. Price does not always equal performance.

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Q: I've created a large spreadsheet (45,000 rows) to do with horseracing, where one column is the race time. The times are data that I have cut and pasted from a racing website. They are expressed as, say, 1:10:13 - representing 1 minute, 10.13 seconds. I would like to convert the times to just seconds, making the above example read 70.13.

A: If you have your entry of 1:10:13 in cell A1, then in A2 put: =Value((Left(A1,1)))*60 + Value(Mid(A1,3,2)) + Value(Right(A1,2))/100. Note that this depends on the format in A2. It should be General and it assumes that the entry in cell A1 is Text and not a time format. It also assumes that the race time will not exceed nine minutes, that is, you cannot have two digits in the minutes field. If the race time can be 10 or more minutes, then you must first determine if the minutes need two digits and then either use an If statement or Find(":",A1) to locate the position of the : and use basic arithmetic to do the calculation.