I'm hoping that the slides are in 35mm format. (If not, most of the specialist scanners for transferring them into digital format cost hundreds, or even thousands, of pounds).
Assuming that they're 35mm, this is probably the cheapest new device:
http://www.amazon.co....qid=1305401320&sr=1-2
or you could try an eBay bid on this:
http://cgi.ebay.co.uk...3&hash=item3a65db03e9
Depending upon how many slides you need to convert (because it's a fairly slow and tedious job) you might try asking around your friends to see if anyone owns a flatbed scanner with a built-in film and slide adapter. (You can't use a 'bog standard' flatbed scanner, as the light needs to pass through the slide, rather than be bounced off it). For example, my own scanner looks like many others but it's got the gizmo that you need:
http://www.canon.co.u...noscan4200f/index.asp
If there are only a handful of slides you could use a commercial company to do the job for you, such as this one:
http://www.digiscanlt...NGY6KgCFYYTfAod1ldUFA
Chris