Can you tell me what malicious activity these apache logs suggest?

what should i do to make sure my server is secure against these attacks. What exactly are they trying to do and how? 221.192.199.35 - - [28/Feb/2010:06:58:24 -0600] "GET http://www.wantsfly.com/prx2.php?hash=080E3B2ABF63DF644337B0560050E1566734C0C63E53 HTTP/1.0" 404 272 "-" "Mozilla/4.0... show more what should i do to make sure my server is secure against these attacks. What exactly are they trying to do and how?

221.192.199.35 - - [28/Feb/2010:06:58:24 -0600] "GET http://www.wantsfly.com/prx2.php?hash=08... HTTP/1.0" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
61.156.31.20 - - [28/Feb/2010:07:21:11 -0600] "GET /manager/html HTTP/1.1" 404 272 "-" "Mozilla/3.0 (compatible; Indy Library)"
208.80.193.37 - - [28/Feb/2010:08:16:51 -0600] "GET / HTTP/1.0" 200 9376 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; {384E6D2F-3389-5FCF-2273-91E14AB57FD5}; .NET CLR 1.1.4322; .NET CLR 2.0.50727)"
221.192.199.35 - - [28/Feb/2010:09:17:24 -0600] "GET http://www.wantsfly.com/prx2.php?hash=08... HTTP/1.0" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
195.127.173.170 - - [28/Feb/2010:10:28:16 -0600] "HEAD / HTTP/1.1" 200 - "-" "oBot"
91.120.21.93 - - [28/Feb/2010:23:38:03 -0600] "GET //phpMyAdmin/ HTTP/1.1" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
91.120.21.93 - - [28/Feb/2010:23:38:03 -0600] "GET //phpmyadmin/ HTTP/1.1" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
91.120.21.93 - - [28/Feb/2010:23:38:04 -0600] "GET //mysql/ HTTP/1.1" 404 267 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
91.120.21.93 - - [28/Feb/2010:23:38:04 -0600] "GET // HTTP/1.1" 200 9376 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
221.192.199.35 - - [01/Mar/2010:01:51:49 -0600] "GET http://www.wantsfly.com/prx2.php?hash=08... HTTP/1.0" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
221.192.199.35 - - [01/Mar/2010:05:38:33 -0600] "GET http://www.wantsfly.com/prx2.php?hash=080E3B2ABF63DF644337B0560050E1566734C0C63E53 HTTP/1.0" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
87.241.235.214 - - [01/Mar/2010:17:51:43 -0600] " " 501 292 "-" "-"
208.80.193.31 - - [01/Mar/2010:21:34:46 -0600] "GET / HTTP/1.0" 200 9376 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; (R1 1.5); .NET CLR 1.1.4322; IEMB3; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; IEMB3)"
221.192.199.35 - - [02/Mar/2010:05:49:07 -0600] "GET http://www.wantsfly.com/prx2.php?hash=080E3B2ABF63DF644337B0560050E1566734C0C63E53 HTTP/1.0" 404 272 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
61.156.31.20 - - [03/Mar/2010:00:47:45 -0600] "GET /manager/html HTTP/1.1" 404 272 "-" "Mozilla/3.0 (compatible; Indy Library)"
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